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1,300 results on '"Ribo, M."'

151. Discovery of TeV gamma-ray emission from the pulsar wind nebula 3C 58 by MAGIC

Author: MAGIC Collaboration, Aleksić, J., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Bangale, P., Barrio, J. A., González, J. Becerra, Bednarek, W., Bernardini, E., Biasuzzi, B., Biland, A., Blanch, O., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., De Lotto, B., Wilhelmi, E. de Oña, Mendez, C. Delgado, Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Eisenacher, D., Elsaesser, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., Galindo, D., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Godinović, N., Muñoz, A. González, Gozzini, S. R., Hadasch, D., Hanabata, Y., Hayashida, M., Herrera, J., Hildebrand, D., Hose, J., Hrupec, D., Idec, W., Kadenius, V., Kellermann, H., Kodani, K., Konno, Y., Krause, J., Kubo, H., Kushida, J., La Barbera, A., Lelas, D., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Lozano, I., Makariev, M., Mallot, K., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Miranda, J. M., Mirzoyan, R., Moralejo, A., Munar-Adrover, P., Nakajima, D., Niedzwiecki, A., Nilsson, K., Nishijima, K., Noda, K., Orito, R., Overkemping, A., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Paredes-Fortuny, X., Persic, M., Moroni, P. G. Prada, Prandini, E., Puljak, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Garcia, J. Rodriguez, Rügamer, S., Saito, T., Saito, K., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Stamatescu, V., Stamerra, A., Steinbring, T., Storz, J., Strzys, M., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thaele, J., Tibolla, O., Torres, D. F., Toyama, T., Treves, A., Uellenbeck, M., Vogler, P., Zanin, R., Martin, J., and Pérez-Torres, M. A.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The pulsar wind nebula (PWN) 3C 58 is one of the historical very-high-energy (VHE; E>100 GeV) gamma-ray source candidates. It is energized by one of the highest spin-down power pulsars known (5% of Crab pulsar) and it has been compared to the Crab Nebula due to their morphological similarities. This object was previously observed by imaging atmospheric Cherenkov telescopes (Whipple, VERITAS and MAGIC), although not detected, with an upper limit of 2.4% Crab Unit (C.U.) at VHE. It was detected by Fermi-LAT with a spectrum extending beyond 100 GeV. We analyzed 81 hours of 3C 58 data taken with the MAGIC telescopes and we detected VHE gamma-ray emission with a significance of 5.7 sigma and an integral flux of 0.65% C.U. above 1 TeV. The differential energy spectrum between 400 GeV and 10 TeV is well described by a power-law function d\phi/dE=f_0(E/1TeV)^{-Gamma} with f_0=(2.0\pm0.4_{stat}\pm0.6_{sys})\times10^{-13}cm^{-2}s^{-1}TeV^{-1} and Gamma=2.4\pm0.2_{stat}\pm0.2_{sys}. The skymap is compatible with an unresolved source. We report the first significant detection of PWN 3C 58 at TeV energies. According to our results 3C 58 is the least luminous VHE gamma-ray PWN ever detected at VHE and the one with the lowest flux at VHE to date. We compare our results with the expectations of time-dependent models in which electrons up-scatter photon fields. The best representation favors a distance to the PWN of 2 kpc and Far Infrared (FIR) comparable to CMB photon fields. If we consider an unexpectedly high FIR density, the data can also be reproduced by models assuming a 3.2 kpc distance. A low magnetic field, far from equipartition, is required to explain the VHE data. Hadronic contribution from the hosting supernova remnant (SNR) requires unrealistic energy budget given the density of the medium, disfavoring cosmic ray acceleration in the SNR as origin of the VHE gamma-ray emission., Comment: 5 pages, 3 figures, accebted by A&A Letters
Published: 2014
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152. Discovery of X-ray emission from the first Be/black hole system

Author: Munar-Adrover, P., Paredes, J. M., Ribó, M., Iwasawa, K., Zabalza, V., and Casares, J.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: MWC 656 (= HD 215227) was recently discovered to be the first binary system composed of a Be star and a black hole (BH). We observed it with \textit{XMM-Newton}, and detected a faint X-ray source compatible with the position of the optical star, thus proving it to be the first Be/BH X-ray binary. The spectrum analysis requires a model fit with two components, a black body plus a power law, with $k_{\rm B}T = 0.07^{+0.04}_{-0.03}$~keV and a photon index $\Gamma= 1.0\pm0.8$, respectively. The non-thermal component dominates above $\simeq$0.8 keV. The obtained total flux is $F(0.3$--$5.5~{\rm keV}) = (4.6^{+1.3}_{-1.1})\times10^{-14}$ erg cm$^{-2}$ s$^{-1}$. At a distance of $2.6\pm0.6$~kpc the total flux translates into a luminosity $L_{\rm X} = (3.7\pm1.7)\times10^{31}$ erg s$^{-1}$. Considering the estimated range of BH masses to be 3.8--6.9 $M_{\odot}$, this luminosity represents $(6.7\pm4.4)\times10^{-8}~L_{\rm Edd}$, which is typical of stellar-mass BHs in quiescence. We discuss the origin of the two spectral components: the thermal component is associated with the hot wind of the Be star, whereas the power law component is associated with emission from the vicinity of the BH. We also find that the position of MWC~656 in the radio versus X-ray luminosity diagram may be consistent with the radio/X-ray correlation observed in BH low-mass X-ray binaries. This suggests that this correlation might also be valid for BH high-mass X-ray binaries (HMXBs) with X-ray luminosities down to $\sim10^{-8} L_{\rm Edd}$. MWC~656 will allow the accretion processes and the accretion/ejection coupling at very low luminosities for BH~HMXBs to be studied., Comment: in press in ApJ Letters, 5 pages, 3 figures
Published: 2014
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153. Multifrequency Studies of the Peculiar Quasar 4C +21.35 During the 2010 Flaring Activity

Author: Ackermann, M., Ajello, M., Allafort, A., Antolini, E., Barbiellini, G., Bastieri, D., Bellazzini, R., Bissaldi, E., Bonamente, E., Bregeon, J., Brigida, M., Bruel, P., Buehler, R., Buson, S., Caliandro, G. A., Cameron, R. A., Caraveo, P. A., Cavazzuti, E., Cecchi, C., Chaves, R. C. G., Chekhtman, A., Chiang, J., Chiaro, G., Ciprini, S., Claus, R., Cohen-Tanugi, J., Conrad, J., Cutini, S., D'Ammando, F., de Palma, F., Dermer, C. D., Silva, E. do Couto e, Donato, D., Drell, P. S., Favuzzi, C., Finke, J., Focke, W. B., Franckowiak, A., Fukazawa, Y., Fusco, P., Gargano, F., Gasparrini, D., Gehrels, N., Giglietto, N., Giordano, F., Giroletti, M., Godfrey, G., Grenier, I. A., Guiriec, S., Hayashida, M., Hewitt, J. W., Horan, D., Hughes, R. E., Iafrate, G., Johnson, A. S., Knodlseder, J., Kuss, M., Lande, J., Larsson, S., Latronico, L., Longo, F., Loparco, F., Lovellette, M. N., Lubrano, P., Mayer, M., Mazziotta, M. N., McEnery, J. E., Michelson, P. F., Mizuno, T., Monzani, M. E., Morselli, A., Moskalenko, I. V., Murgia, S., Nemmen, R., Nuss, E., Ohsugi, T., Orienti, M., Orlando, E., Perkins, J. S., Pesce-Rollins, M., Piron, F., Pivato, G., Porter, T. A., Rainò, S., Razzano, M., Reimer, A., Reimer, O., Sanchez, D. A., Schulz, A., Sgrò, C., Siskind, E. J., Spandre, G., Spinelli, P., Stawarz, L., Takahashi, H., Takahashi, T., Thayer, J. G., Thayer, J. B., Thompson, D. J., Tinivella, M., Torres, D. F., Tosti, G., Troja, E., Usher, T. L., Vandenbroucke, J., Vasileiou, V., Vianello, G., Vitale, V., Werner, M., Winer, B. L., Wood, D. L., Wood, K. S., Aleksic, J., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Bangale, P., de Almeida, U. Barres, Barrio, J. A., Gonzalez, J. Becerra, Bednarek, W., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Carmona, E., Carosi, A., Fidalgo, D. Carreto, Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., De Lotto, B., Mendez, C. Delgado, Doert, M., Dominguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Eisenacher, D., Elsaesser, D., Farina, E., Ferenc, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., Lopez, R. J. Garcia, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Giavitto, G., Godinovic, N., Munoz, A. Gonzalez, Gozzini, S. R., Hadasch, D., Herrero, A., Hildebrand, D., Hose, J., Hrupec, D., Idec, W., Kadenius, V., Kellermann, H., Knoetig, M. L., Kodani, K., Konno, Y., Krause, J., Kubo, H., Kushida, J., La Barbera, A., Lelas, D., Lewandowska, N., Lindfors, E., Lombardi, S., Lopez, M., Lopez-Coto, R., Lopez-Oramas, A., Lorenz, E., Lozano, I., Makariev, M., Mallot, K., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martinez, M., Mazin, D., Menzel, U., Meucci, M., Miranda, J. M., Mirzoyan, R., Moralejo, A., Munar-Adrover, P., Nakajima, D., Niedzwiecki, A., Nishijima, K., Nilsson, K., Nowak, N., Orito, R., Overkemping, A., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Paredes-Fortuny, X., Partini, S., Persic, M., Prada, F., Moroni, P. G. Prada, Prandini, E., Preziuso, S., Puljak, I., Reinthal, R., Rhode, W., Ribo, M., Rico, J., Garcia, J. Rodriguez, Rugamer, S., Saggion, A., Saito, T., Saito, K., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpaa, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Stamatescu, V., Stamerra, A., Steinbring, T., Storz, J., Sun, S., Suric, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzic, T., Tescaro, D., Teshima, M., Thaele, J., Tibolla, O., Toyama, T., Treves, A., Vogler, P., Wagner, R. M., Zandanel, F., Zanin, R., Aller, M. F., Angelakis, E., Blinov, D. A., Djorgovski, S. G., Drake, A. J., Efimova, N. V., Gurwell, M. A., Homan, D. C., Jordan, B., Kopatskaya, E. N., Kovalev, Y. Y., Kurtanidze, O. M., Lahteenmaki, A., Larionov, V. M., Lister, M. L., Nieppola, E., Nikolashvili, M. G., Ros, E., Savolainen, T., Sigua, L. A., and Tornikoski, M.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics, Astrophysics - Astrophysics of Galaxies
Abstract: The discovery of rapidly variable Very High Energy (VHE; E > 100 GeV) gamma-ray emission from 4C +21.35 (PKS 1222+216) by MAGIC on 2010 June 17, triggered by the high activity detected by the Fermi Large Area Telescope (LAT) in high energy (HE; E > 100 MeV) gamma-rays, poses intriguing questions on the location of the gamma-ray emitting region in this flat spectrum radio quasar. We present multifrequency data of 4C +21.35 collected from centimeter to VHE during 2010 to investigate the properties of this source and discuss a possible emission model. The first hint of detection at VHE was observed by MAGIC on 2010 May 3, soon after a gamma-ray flare detected by Fermi-LAT that peaked on April 29. The same emission mechanism may therefore be responsible for both the HE and VHE emission during the 2010 flaring episodes. Two optical peaks were detected on 2010 April 20 and June 30, close in time but not simultaneous with the two gamma-ray peaks, while no clear connection was observed between the X-ray an gamma-ray emission. An increasing flux density was observed in radio and mm bands from the beginning of 2009, in accordance with the increasing gamma-ray activity observed by Fermi-LAT, and peaking on 2011 January 27 in the mm regime (230 GHz). We model the spectral energy distributions (SEDs) of 4C +21.35 for the two periods of the VHE detection and a quiescent state, using a one-zone model with the emission coming from a very compact region outside the broad line region. The three SEDs can be fit with a combination of synchrotron self-Compton and external Compton emission of seed photons from a dust torus, changing only the electron distribution parameters between the epochs. The fit of the optical/UV part of the spectrum for 2010 April 29 seems to favor an inner disk radius of <6 gravitational radii, as one would expect from a prograde-rotating Kerr black hole., Comment: 46 pages, 10 figures, 4 tables. The Astrophysical Journal, Volume 786, Issue 2, article id. 157, 17 pp. Contact Authors: Filippo D'Ammando, Justin Finke, Davide Donato, Josefa Becerra Gonzalez, Tomislav Terzic. Figure 1 updated
Published: 2014
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154. Detection of bridge emission above 50 GeV from the Crab pulsar with the MAGIC telescopes

Author: Aleksić, J., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Bangale, P., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Bernardini, E., Biasuzzi, B., Biland, A., Blanch, O., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., De Lotto, B., Mendez, C. Delgado, Doert, M., Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Eisenacher, D., Elsaesser, D., Farina, E., Ferenc, D., Fidalgo, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Godinović, N., Muñoz, A. González, Gozzini, S. R., Hadasch, D., Hayashida, M., Herrera, J., Herrero, A., Hildebrand, D., Hirotani, K., Hose, J., Hrupec, D., Idec, W., Kadenius, V., Kellermann, H., Kodani, K., Konno, Y., Krause, J., Kubo, H., Kushida, J., La Barbera, A., Lelas, D., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Lozano, I., Makariev, M., Mallot, K., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Miranda, J. M., Mirzoyan, R., Moralejo, A., Munar-Adrover, P., Nakajima, D., Niedzwiecki, A., Nilsson, K., Nishijima, K., Noda, K., Nowak, N., Orito, R., Overkemping, A., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Paredes-Fortuny, X., Partini, S., Persic, M., Moroni, P. G. Prada, Prandini, E., Preziuso, S., Puljak, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Garcia, J. Rodriguez, Rügamer, S., Saggion, A., Saito, T. Y., Saito, K., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Stamatescu, V., Stamerra, A., Steinbring, T., Storz, J., Strzys, M., Sun, S., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thaele, J., Tibolla, O., Torres, D. F., Toyama, T., Treves, A., Uellenbeck, M., Vogler, P., Wagner, R. M., and Zanin, R.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The Crab pulsar is the only astronomical pulsed source detected at very high energy (VHE, E>100GeV) gamma-rays. The emission mechanism of VHE pulsation is not yet fully understood, although several theoretical models have been proposed. In order to test the new models, we measured the light curve and the spectra of the Crab pulsar with high precision by means of deep observations. We analyzed 135 hours of selected MAGIC data taken between 2009 and 2013 in stereoscopic mode. In order to discuss the spectral shape in connection with lower energies, 4.6 years of {\it Fermi}-LAT data were also analyzed. The known two pulses per period were detected with a significance of $8.0 \sigma$ and $12.6 \sigma$. In addition, significant emission was found between the two pulses with $6.2 \sigma$. We discovered the bridge emission above 50 GeV between the two main pulses. This emission can not be explained with the existing theories. These data can be used for testing new theoretical models., Comment: 5 pages, 4 figures
Published: 2014
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155. Search for Very-High-Energy Gamma Rays from the z = 0.896 Quasar 4C +55.17 with the MAGIC telescopes

Author: MAGIC Collaboration, Aleksić, J., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Bangale, P., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Carmona, E., Carosi, A., Fidalgo, D. Carreto, Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., De Lotto, B., Mendez, C. Delgado, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Eisenacher, D., Elsaesser, D., Farina, E., Ferenc, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Giavitto, G., Godinović, N., noz, A. González Mu\, Gozzini, S. R., Hadasch, D., Hayashida, M., Herrero, A., Hildebrand, D., Hose, J., Hrupec, D., Idec, W., Kadenius, V., Kellermann, H., Knoetig, M. L., Kodani, K., Konno, Y., Krause, J., Kubo, H., Kushida, J., La Barbera, A., Lelas, D., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Lozano, I., Makariev, M., Mallot, K., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Meucci, M., Miranda, J. M., Mirzoyan, R., Moralejo, A., Munar-Adrover, P., Nakajima, D., Niedzwiecki, A., Nilsson, K., Nishijima, K., Nowak, N., Orito, R., Overkemping, A., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Paredes-Fortuny, X., Partini, S., Persic, M., Prada, F., Moroni, P. G. Prada, Prandini, E., Preziuso, S., Puljak, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Garcia, J. Rodriguez, Rügamer, S., Saggion, A., Saito, T., Saito, K., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Stamatescu, V., Stamerra, A., Steinbring, T., Storz, J., Sun, S., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thaele, J., Tibolla, O., Torres, D. F., Toyama, T., Treves, A., Vogler, P., Wagner, R. M., Zandanel, F., and Zanin, R.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
Abstract: The bright gamma-ray quasar 4C +55.17 is a distant source ($z = 0.896$) with a hard spectrum at GeV energies as observed by the Large Area Telescope (LAT) on board the {{\it Fermi}} satellite. This source is identified as a good source candidate for very-high-energy (VHE; $> 30$ GeV) gamma rays. In general VHE gamma rays from distant sources provide an unique opportunity to study the extragalactic background light (EBL) and underlying astrophysics. The flux intensity of this source in the VHE range is investigated. Then, constraints on the EBL are derived from the attenuation of gamma-ray photons coming from the distant blazar. We searched for a gamma-ray signal from this object using the 35-hour observations taken by the MAGIC telescopes between November 2010 and January 2011. No significant VHE gamma-ray signal was detected. We computed the upper limits of the integrated gamma-ray flux at $95\%$ confidence level of $9.4 \times 10^{-12}$ cm$^{-2}$ s$^{-1}$ and $2.5 \times 10^{-12}$ cm$^{-2}$ s$^{-1}$ above $100$ GeV and $200$ GeV, respectively. The differential upper limits in four energy bins in the range from $80$ GeV to $500$ GeV are also derived. The upper limits are consistent with the attenuation predicted by low-flux EBL models on the assumption of a simple power-law spectrum extrapolated from LAT data., Comment: 7 pages, 3 figures, accepted for publication in MNRAS
Published: 2014
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156. MAGIC reveals a complex morphology within the unidentified gamma-ray source HESS J1857+026

Author: MAGIC Collaboration, Aleksić, J., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Bangale, P., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Bernardini, E., Biland, A., Blanch, O., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., De Lotto, B., Mendez, C. Delgado, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Eisenacher, D., Elsaesser, D., Farina, E., Ferenc, D., Carreto, D. Fidalgo, Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Godinović, N., Muñoz, A. González, Gozzini, S. R., Hadasch, D., Hayashida, M., Herrera, J., Herrero, A., Hildebrand, D., Hose, J., Hrupec, D., Idec, W., Kadenius, V., Kellermann, H., Klepser, S., Kodani, K., Konno, Y., Krause, J., Kubo, H., Kushida, J., La Barbera, A., Lelas, D., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Lozano, I., Makariev, M., Mallot, K., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Meucci, M., Miranda, J. M., Mirzoyan, R., Moralejo, A., Munar-Adrover, P., Nakajima, D., Niedzwiecki, A., Nilsson, K., Nishijima, K., Noda, K., Nowak, N., Wilhelmi, E. de Oña, Orito, R., Overkemping, A., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Paredes-Fortuny, X., Partini, S., Persic, M., Prada, F., Moroni, P. G. Prada, Prandini, E., Preziuso, S., Puljak, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Garcia, J. Rodriguez, Rügamer, S., Saggion, A., Saito, T., Saito, K., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Stamatescu, V., Stamerra, A., Steinbring, T., Storz, J., Strzys, M., Sun, S., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thaele, J., Tibolla, O., Torres, D. F., Toyama, T., Treves, A., Uellenbeck, M., Vogler, P., Wagner, R. M., Zandanel, F., and Zanin, R.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: HESS J1857+026 is an extended TeV gamma-ray source that was discovered by H.E.S.S. as part of its Galactic plane survey. Given its broadband spectral energy distribution and its spatial coincidence with the young energetic pulsar PSR J1856+0245, the source has been put forward as a pulsar wind nebula (PWN) candidate. MAGIC has performed follow-up observations aimed at mapping the source down to energies approaching 100 GeV in order to better understand its complex morphology. HESS J1857+026 was observed by MAGIC in 2010, yielding 29 hours of good quality stereoscopic data that allowed us to map the source region in two separate ranges of energy. We detected very-high-energy gamma-ray emission from HESS J1857+026 with a significance of $12 \sigma$ above $150$ GeV. The differential energy spectrum between $100$ GeV and $13$ TeV is well described by a power law function $dN/dE = N_0(E/1\textrm{TeV})^{-\Gamma}$ with $N_0 = (5.37 \pm0.44_{stat} \pm1.5_{sys}) \times 10^{-12} (\textrm{TeV}^{-1} \textrm{cm}^{-2}$ $\textrm{ s}^{-1})$ and $\Gamma = 2.16\pm0.07_{stat} \pm0.15_{sys}$, which bridges the gap between the GeV emission measured by Fermi-LAT and the multi-TeV emission measured by H.E.S.S.. In addition, we present a detailed analysis of the energy-dependent morphology of this region. We couple these results with archival multi-wavelength data and outline evidence in favor of a two-source scenario, whereby one source is associated with a PWN, while the other could be linked with a molecular cloud complex containing an HII region and a possible gas cavity., Comment: 9 pages, 6 figures. Accepted for publication in A&A
Published: 2014
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157. MAGIC gamma-ray and multifrequency observations of flat spectrum radio quasar PKS 1510-089 in early 2012

Author: MAGIC Collaboration, Aleksić, J., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Bangale, P., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Bernardini, E., Biland, A., Blanch, O., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Carmona, E., Carosi, A., Carreto-Fidalgo, D., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., De Lotto, B., Mendez, C. Delgado, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Eisenacher, D., Elsaesser, D., Farina, E., Ferenc, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Godinović, N., Muñoz, A. González, Gozzini, S. R., Hadasch, D., Hayashida, M., Herrera, J., Herrero, A., Hildebrand, D., Hose, J., Hrupec, D., Idec, W., Kadenius, V., Kellermann, H., Kodani, K., Konno, Y., Krause, J., Kubo, H., Kushida, J., La Barbera, A., Lelas, D., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Lozano, I., Makariev, M., Mallot, K., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Meucci, M., Miranda, J. M., Mirzoyan, R., Moralejo, A., Munar-Adrover, P., Nakajima, D., Niedzwiecki, A., Nilsson, K., Nishijima, K., Noda, K., Nowak, N., Orito, R., Overkemping, A., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Paredes-Fortuny, X., Partini, S., Persic, M., Prada, F., Moroni, P. G. Prada, Prandini, E., Preziuso, S., Puljak, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Garcia, J. Rodriguez, Rügamer, S., Saggion, A., Saito, T., Saito, K., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Stamatescu, V., Stamerra, A., Steinbring, T., Storz, J., Strzys, M., Sun, S., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thaele, J., Tibolla, O., Torres, D. F., Toyama, T., Treves, A., Uellenbeck, M., Vogler, P., Wagner, R. M., Zandanel, F., Zanin, R., Lucarelli, F., Pittori, C., Vercellone, S., Verrecchia, F., Buson, S., D'Ammando, F., Stawarz, L., Giroletti, M., Orienti, M., Mundell, C., Steele, I., Zarpudin, B., Raiteri, C. M., Villata, M., Sandrinelli, A., Lähteenäki, A., Tammi, J., Tornikoski, M., Hovatta, T., Readhead, A. C. S., Max-Moerbeck, W., Richards, J. L., Jorstad, S., Marscher, A., Gurwell, M. A., Larionov, V. M., Blinov, D. A., Konstantinova, T. S., Kopatskaya, E. N., Larionova, L. V., Larionova, E. G., Morozova, D. A., Troitsky, I. S., Mokrushina, A. A., Pavlova, Yu. V., Chen, W. P., Lin, H. C., Panwar, N., Agudo, I., Casadio, C., Gómez, J. L., Molina, S. N., Kurtanidze, O. M., Nikolashvili, M. G., Kurtanidze, S. O., Chigladze, R. A., Acosta-Pulido, J. A., Carnerero, M. I., Manilla-Robles, A., Ovcharov, E., Bozhilov, V., Metodieva, I., Aller, M. F., Aller, H. D., Fuhrmann, L., Angelakis, E., Nestoras, I., Krichbaum, T. P., Zensus, J. A., Ungerechts, H., Sievers, A., and Riquelme, D.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Among more than fifty blazars detected in very high energy (VHE, E>100GeV) gamma-rays, only three belong to the subclass of Flat Spectrum Radio Quasars (FSRQs). MAGIC observed FSRQ PKS 1510-089 in February-April 2012 during a high activity state in the high energy (HE, E>100 MeV) gamma-ray band observed by AGILE and Fermi. MAGIC observations result in the detection of a source with significance of 6.0 sigma. In agreement with the previous VHE observations of the source, we find no statistically significant variability during the MAGIC observations in daily, weekly or monthly time scales. The other two known VHE FSRQs have shown daily scale to sub-hour variability. We study the multifrequency behaviour of the source at the epoch of MAGIC observation, collecting quasi-simultaneous data at radio and optical (GASP-WEBT and F-Gamma collaborations, REM, Steward, Perkins, Liverpool, OVRO and VLBA telescopes), X-ray (Swift satellite) and HE gamma-ray frequencies. The gamma-ray SED combining AGILE, Fermi and MAGIC data joins smoothly and shows no hint of a break. The multifrequency light curves suggest a common origin for the millimeter radio and HE gamma-ray emission and the HE gamma-ray flaring starts when the new component is ejected from the 43GHz VLBA core. The quasi-simultaneous multifrequency SED is modelled with a one-zone inverse Compton model. We study two different origins of the seed photons for the inverse Compton scattering, namely the infra-red torus and a slow sheath surrounding the jet around the VLBA core. Both models fit the data well. However, the fast HE gamma-ray variability requires that within the modelled large emitting region, there must exist more compact regions. We suggest that these observed signatures would be most naturally explained by a turbulent plasma flowing at a relativistic speed down the jet and crossing a standing conical shock., Comment: 21 pages, 15 figures, A&A in press
Published: 2014
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158. A Be-type star with a black hole companion

Author: Casares, J., Negueruela, I., Ribo, M., Ribas, I., Paredes, J. M., Herrero, A., and Simon-Diaz, S.
Subjects: Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Galaxy Astrophysics
Abstract: Stellar-mass black holes have all been discovered through X-ray emission, which arises from the accretion of gas from their binary companions (this gas is either stripped from low-mass stars or supplied as winds from massive ones). Binary evolution models also predict the existence of black holes accreting from the equatorial envelope of rapidly spinning Be-type stars (stars of the Be type are hot blue irregular variables showing characteristic spectral emission lines of hydrogen). Of the ~80 Be X-ray binaries known in the Galaxy, however, only pulsating neutron stars have been found as companions. A black hole was formally allowed as a solution for the companion to the Be star MWC 656 (also known as HD 215227), although that was based on a single radial velocity curve of the Be star, a mistaken spectral classification and rough estimates of the inclination angle. Here we report observations of an accretion disk line mirroring the orbit of the Be star. This, together with an improved radial velocity curve of the Be star through fitting sharp Fe II profiles from the equatorial disk, and a refined Be classification (to that of a B1.5-B2 III star), reveals a black hole of 3.8 to 6.9 solar masses orbiting MWC 656, the candidate counterpart of the gamma-ray source AGL J2241+4454. The black hole is X-ray quiescent and fed by a radiatively inefficient accretion flow giving a luminosity less than 1.6 x 10-7 times the Eddington luminosity. This implies that Be binaries with black-hole companions are difficult to detect by conventional X-ray surveys., Comment: To appear in Nature January 16, 2014. 25 pages, 6 figures and 3 tables, including Methods section and Extended Data. This is the author's version of the work
Published: 2014
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159. Multi-wavelength observations of the binary system PSR B1259-63/LS 2883 around the 2010-2011 periastron passage

Author: Chernyakova, M., Abdo, A. A., Neronov, A., McSwain, M. V., Moldón, J., Ribó, M., Paredes, J. M., Sushch, I., de Naurois, M., Schwanke, U., Uchiyama, Y., Wood, K., Johnston, S., Chaty, S., Coleiro, A., Malyshev, D., and Babyk, Iu.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report on broad multi-wavelength observations of the 2010-2011 periastron passage of the gamma-ray loud binary system PSR B1259-63. High resolution interferometric radio observations establish extended radio emission trailing the position of the pulsar. Observations with the Fermi Gamma-ray Space Telescope reveal GeV gamma-ray flaring activity of the system, reaching the spin-down luminosity of the pulsar, around 30 days after periastron. There are no clear signatures of variability at radio, X-ray and TeV energies at the time of the GeV flare. Variability around periastron in the H$\alpha$ emission line, can be interpreted as the gravitational interaction between the pulsar and the circumstellar disk. The equivalent width of the H$\alpha$ grows from a few days before periastron until a few days later, and decreases again between 18 and 46 days after periastron. In near infrared we observe the similar decrease of the equivalent width of Br$\gamma$ line between the 40th and 117th day after the periastron. For the idealized disk, the variability of the H$\alpha$ line represents the variability of the mass and size of the disk. We discuss possible physical relations between the state of the disk and GeV emission under assumption that GeV flare is directly related to the decrease of the disk size., Comment: accepted to MNRAS
Published: 2014
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160. MAGIC long-term study of the distant TeV blazar PKS 1424+240 in a multiwavelength context

Author: MAGIC Collaboration, Aleksić, J., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Bangale, P., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Bernardini, E., Biland, A., Blanch, O., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Carmona, E., Carosi, A., Fidalgo, D. Carreto, Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., De Lotto, B., Mendez, C. Delgado, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Eisenacher, D., Elsaesser, D., Farina, E., Ferenc, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Godinović, N., Muñoz, A. González, Gozzini, S. R., Hadasch, D., Hayashida, M., Herrera, J., Herrero, A., Hildebrand, D., Hose, J., Hrupec, D., Idec, W., Kadenius, V., Kellermann, H., Kodani, K., Konno, Y., Krause, J., Kubo, H., Kushida, J., La Barbera, A., Lelas, D., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Lozano, I., Makariev, M., Mallot, K., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Meucci, M., Miranda, J. M., Mirzoyan, R., Moralejo, A., Munar-Adrover, P., Nakajima, D., Niedzwiecki, A., Nilsson, K., Nishijima, K., Noda, K., Nowak, N., Orito, R., Overkemping, A., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Paredes-Fortuny, X., Partini, S., Persic, M., Prada, F., Moroni, P. G. Prada, Prandini, E., Preziuso, S., Puljak, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Garcia, J. Rodriguez, Rügamer, S., Saggion, A., Saito, T., Saito, K., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Stamatescu, V., Stamerra, A., Steinbring, T., Storz, J., Sun, S., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thaele, J., Tibolla, O., Torres, D. F., Toyama, T., Treves, A., Uellenbeck, M., Vogler, P., Wagner, R. M., Zandanel, F., Zanin, R., Cutini, S., Gasparrini, D., Furniss, A., Hovatta, T., Kangas, T., Kankare, E., Kotilainen, J., Lister, M., Lähteenmäki, A., Max-Moerbeck, W., Pavlidou, V., Readhead, A., and Richards, J.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: We present a study of the very high energy (VHE; E > 100 GeV) gamma-ray emission of the blazar PKS 1424+240 observed with the MAGIC telescopes. The primary aim of this paper is the multiwavelength spectral characterization and modeling of this blazar, which is made particularly interesting by the recent discovery of a lower limit of its redshift of z > 0.6 and makes it a promising candidate to be the most distant VHE source. The source has been observed with the MAGIC telescopes in VHE gamma rays for a total observation time of ~33.6 h from 2009 to 2011. The source was marginally detected in VHE gamma rays during 2009 and 2010, and later, the detection was confirmed during an optical outburst in 2011. The combined significance of the stacked sample is ~7.2 sigma. The differential spectra measured during the different campaigns can be described by steep power laws with the indices ranging from 3.5 +/- 1.2 to 5.0 +/- 1.7. The MAGIC spectra corrected for the absorption due to the extragalactic background light connect smoothly, within systematic errors, with the mean spectrum in 2009-2011 observed at lower energies by the Fermi-LAT. The absorption-corrected MAGIC spectrum is flat with no apparent turn down up to 400 GeV. The multiwavelength light curve shows increasing flux in radio and optical bands that could point to a common origin from the same region of the jet. The large separation between the two peaks of the constructed non-simultaneous spectral energy distribution also requires an extremely high Doppler factor if an one zone synchrotron self-Compton model is applied. We find that a two-component synchrotron self-Compton model describes the spectral energy distribution of the source well, if the source is located at z~0.6., Comment: 15 pages, 8 figures. A&A accepted for publication
Published: 2014
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161. Deep GMRT radio observations and a multi-wavelength study of the region around HESS J1858+020

Author: Paredes, J. M., Ishwara-Chandra, C. H., Bosch-Ramon, V., Zabalza, V., Iwasawa, K., and Ribo, M.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: There are a number of very high energy sources in the Galaxy that remain unidentified. Multi-wavelength and variability studies, and catalogue searches, are powerful tools to identify the physical counterpart, given the uncertainty in the source location and extension. This work carries out a thorough multi-wavelength study of the unidentified, very high energy source HESS J1858+020 and its environs. Giant Metrewave Radio Telescope observations at 610 MHz and 1.4 GHz have been done to obtain a deep, low-frequency radio image of the region surrounding HESS J1858+020. Archival radio, infrared, and X-ray data have been analysed as well. This observational information, combined with molecular data, catalogue sources, and a nearby Fermi gamma-ray detection of unidentified origin, are combined to explore possible counterparts to the very high energy source. We provide with a deep radio image of a supernova remnant that might be related to the GeV and TeV emission in the region. We confirm the presence of an H II region next to the supernova remnant and coincident with molecular emission. A potential region of star formation is also identified. We identify several radio and X-ray sources in the surroundings. Some of these sources are known planetary nebulae, whereas others may be non-thermal extended emitters and embedded young stellar objects. Three old, background Galactic pulsars also neighbour HESS J1858+020 along the line of sight. The region surrounding HESS J1858+020 is rich in molecular structures and non-thermal objects that may potentially be linked to this unidentified very high energy source. In particular, a supernova remnant interacting with nearby molecular clouds may be a good candidate, but a star forming region, or a non-thermal radio source of yet unclear nature, may also be behind the gamma-ray source. Further observational studies are needed., Comment: 8 pages, 5 figures. Accepted for publication in A&A
Published: 2013
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162. Optimized dark matter searches in deep observations of Segue 1 with MAGIC

Author: Aleksić, J., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Bangale, P., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Carmona, E., Carosi, A., Fidalgo, D. Carreto, Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., De Lotto, B., Mendez, C. Delgado, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Eisenacher, D., Elsaesser, D., Farina, E., Ferenc, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Giavitto, G., Godinović, N., Muñoz, A. González, Gozzini, S. R., Hadasch, D., Hayashida, M., Herrero, A., Hildebrand, D., Hose, J., Hrupec, D., Idec, W., Kadenius, V., Kellermann, H., Kodani, K., Konno, Y., Krause, J., Kubo, H., Kushida, J., La Barbera, A., Lelas, D., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Lozano, I., Makariev, M., Mallot, K., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Meucci, M., Miranda, J. M., Mirzoyan, R., Moralejo, A., Munar-Adrover, P., Nakajima, D., Niedzwiecki, A., Nilsson, K., Nishijima, K., Nowak, N., Orito, R., Overkemping, A., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Paredes-Fortuny, X., Partini, S., Persic, M., Prada, F., Moroni, P. G. Prada, Prandini, E., Preziuso, S., Puljak, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Garcia, J. Rodriguez, Rügamer, S., Saggion, A., Saito, T., Saito, K., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Stamatescu, V., Stamerra, A., Steinbring, T., Storz, J., Sun, S., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thaele, J., Tibolla, O., Torres, D. F., Toyama, T., Treves, A., Uellenbeck, M., Vogler, P., Wagner, R. M., Zandanel, F., Zanin, R., and Ibarra, A.
Subjects: High Energy Physics - Phenomenology, Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present the results of stereoscopic observations of the satellite galaxy Segue 1 with the MAGIC Telescopes, carried out between 2011 and 2013. With almost 160 hours of good-quality data, this is the deepest observational campaign on any dwarf galaxy performed so far in the very high energy range of the electromagnetic spectrum. We search this large data sample for signals of dark matter particles in the mass range between 100 GeV and 20 TeV. For this we use the full likelihood analysis method, which provides optimal sensitivity to characteristic gamma-ray spectral features, like those expected from dark matter annihilation or decay. In particular, we focus our search on gamma-rays produced from different final state Standard Model particles, annihilation with internal bremsstrahlung, monochromatic lines and box-shaped signals. Our results represent the most stringent constraints to the annihilation cross-section or decay lifetime obtained from observations of satellite galaxies, for masses above few hundred GeV. In particular, our strongest limit (95% confidence level) corresponds to a ~500 GeV dark matter particle annihilating into tau+tau-, and is of order ~ 1.2x10^{-24} cm^3 s^{-1} - a factor ~40 above the thermal value., Comment: 32 pages, 19 figures
Published: 2013
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163. Observations of VHE gamma-ray binaries with the MAGIC Telescopes

Author: López-Oramas, A., Bigas, O. Blanch, Cortina, J., Hadasch, D., Herrero, A., Marcote, B., Munar-Adrover, P., Moldón, J., Paredes, J. M., Ribas, I., Ribó, M., Torres, D., and Zanin, R.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Several binary systems, composed of a star and a compact object, have been detected in the GeV-TeV range. Several systems have been observed but only a handful of sources have shown emission at those energies. Here, we present the observations conducted by MAGIC of different {\gamma}-ray binary systems. On one hand, we show the latest studies on the binary system LS I +61 303, which displays variability on different timescales. With the latest MAGIC observations, we will try to shed light on our understanding of this source, by presenting super-orbital and multi-wavelength studies. On the other hand, we show the observational results on the binary system HD 215227. This source has been proposed as a new {\gamma}-ray binary for being spatially coincident with the gamma-ray source AGL J2241+4454 detected by AGILE at E >100 GeV., Comment: ICRC 2013 Proceedings
Published: 2013

164. MAGIC upper limits on the GRB 090102 afterglow

Author: MAGIC Collaboration, Aleksić, J., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Bangale, P., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Carmona, E., Carosi, A., Fidalgo, D. Carreto, Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., De Lotto, B., Mendez, C. Delgado, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Eisenacher, D., Elsaesser, D., Farina, E., Ferenc, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Giavitto, G., Godinović, N., Muñoz, A. González, Gozzini, S. R., Hadasch, D., Hayashida, M., Herrero, A., Hildebrand, D., Hose, J., Hrupec, D., Idec, W., Kadenius, V., Kellermann, H., Knoetig, M. L., Kodani, K., Konno, Y., Krause, J., Kubo, H., Kushida, J., La Barbera, A., Lelas, D., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Lozano, I., Makariev, M., Mallot, K., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Meucci, M., Miranda, J. M., Mirzoyan, R., Moralejo, A., Munar-Adrover, P., Nakajima, D., Niedzwiecki, A., Nilsson, K., Nishijima, K., Nowak, N., Orito, R., Overkemping, A., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Paredes-Fortuny, X., Partini, S., Persic, M., Prada, F., Moroni, P. G. Prada, Prandini, E., Preziuso, S., Puljak, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Garcia, J. Rodriguez, Rügamer, S., Saggion, A., Saito, T., Saito, K., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Stamatescu, V., Stamerra, A., Steinbring, T., Storz, J., Sun, S., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thaele, J., Tibolla, O., Torres, D. F., Toyama, T., Treves, A., Vogler, P., Wagner, R. M., Zandanel, F., Zanin, R., Bouvier, A., Tajima, H., and Longo, F.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Indications of a GeV component in the emission from GRBs are known since the EGRET observations during the 1990's and they have been confirmed by the data of the Fermi satellite. These results have, however, shown that our understanding of GRB physics is still unsatisfactory. The new generation of Cherenkov observatories and in particular the MAGIC telescope, allow for the first time the possibility to extend the measurement of GRBs from several tens up to hundreds of GeV energy range. Both leptonic and hadronic processes have been suggested to explain the possible GeV/TeV counterpart of GRBs. Observations with ground-based telescopes of very high energy photons (E>30 GeV) from these sources are going to play a key role in discriminating among the different proposed emission mechanisms, which are barely distinguishable at lower energies. MAGIC telescope observations of the GRB 090102 (z=1.547) field and Fermi Large Area Telescope (LAT) data in the same time interval are analysed to derive upper limits of the GeV/TeV emission. We compare these results to the expected emissions evaluated for different processes in the framework of a relativistic blast wave model for the afterglow. Simultaneous upper limits with Fermi and a Cherenkov telescope have been derived for this GRB observation. The results we obtained are compatible with the expected emission although the difficulties in predicting the HE and VHE emission for the afterglow of this event makes it difficult to draw firmer conclusions. Nonetheless, MAGIC sensitivity in the energy range of overlap with space-based instruments (above about 40 GeV) is about one order of magnitude better with respect to Fermi. This makes evident the constraining power of ground-based observations and shows that the MAGIC telescope has reached the required performance to make possible GRB multiwavelength studies in the very high energy range., Comment: 8 pages, 5 figures, 2 tables. Submitted to MNRAS
Published: 2013
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165. MAGIC observations and multifrequency properties of the Flat Spectrum Radio Quasar 3C 279 in 2011

Author: Aleksić, J., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Bangale, P., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Carmona, E., Carosi, A., Fidalgo, D. Carreto, Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., De Lotto, B., Mendez, C. Delgado, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Eisenacher, D., Elsaesser, D., Farina, E., Ferenc, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Giavitto, G., Godinović, N., Muñoz, A. González, Gozzini, S. R., Hadasch, D., Herrero, A., Hildebrand, D., Hose, J., Hrupec, D., Idec, W., Kadenius, V., Kellermann, H., Knoetig, M. L., Kodani, K., Konno, Y., Krause, J., Kubo, H., Kushida, J., La Barbera, A., Lelas, D., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Lozano, I., Makariev, M., Mallot, K., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Meucci, M., Miranda, J. M., Mirzoyan, R., Moralejo, A., Munar-Adrover, P., Nakajima, D., Niedzwiecki, A., Nilsson, K., Nishijima, K., Nowak, N., Orito, R., Overkemping, A., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Paredes-Fortuny, X., Partini, S., Persic, M., Prada, F., Moroni, P. G. Prada, Prandini, E., Preziuso, S., Puljak, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Garcia, J. Rodriguez, Rügamer, S., Saggion, A., Saito, T., Saito, K., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Stamatescu, V., Stamerra, A., Steinbring, T., Storz, J., Sun, S., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thaele, J., Tibolla, O., Torres, D. F., Toyama, T., Treves, A., Vogler, P., Wagner, R. M., Zandanel, F., Zanin, R., Berdyugin, A., Vornanen, T., Lähteenmäki, A., Tammi, J., Tornikoski, M., Hovatta, T., Max-Moerbeck, W., Readhead, A., Richards, J., Hayashida, M., Sanchez, D. A., Marscher, A., and Jorstad, S.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
Abstract: We study the multifrequency emission and spectral properties of the quasar 3C 279. We observed 3C 279 in very high energy (VHE, E>100GeV) gamma rays, with the MAGIC telescopes during 2011, for the first time in stereoscopic mode. We combine these measurements with observations at other energy bands: in high energy (HE, E>100MeV) gamma rays from Fermi-LAT, in X-rays from RXTE, in the optical from the KVA telescope and in the radio at 43GHz, 37GHz and 15GHz from the VLBA, Mets\"ahovi and OVRO radio telescopes and optical polarisation measurements from the KVA and Liverpool telescopes. During the MAGIC observations (February to April 2011) 3C 279 was in a low state in optical, X-ray and gamma rays. The MAGIC observations did not yield a significant detection. These upper limits are in agreement with the extrapolation of the HE gamma-ray spectrum, corrected for extragalactic background light absorption, from Fermi-LAT. The second part of the MAGIC observations in 2011 was triggered by a high activity state in the optical and gamma-ray bands. During the optical outburst the optical electric vector position angle rotatated of about 180 degrees. There was no simultaneous rotation of the 43GHz radio polarisation angle. No VHE gamma rays were detected by MAGIC, and the derived upper limits suggest the presence of a spectral break or curvature between the Fermi-LAT and MAGIC bands. The combined upper limits are the strongest derived to date for the source at VHE and below the level of the previously detected flux by a factor 2. Radiation models that include synchrotron and inverse Compton emissions match the optical to gamma-ray data, assuming an emission component inside the broad line region (BLR) responsible for the high-energy emission and one outside the BLR and the infrared torus causing optical and low-energy emission. We interpreted the optical polarisation with a bent trajectory model., Comment: 15 pages, 11 figures, 5 tables; A&A in press
Published: 2013
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166. Contemporaneous observations of the radio galaxy NGC 1275 from radio to very high energy gamma-rays

Author: MAGIC Collaboration, Aleksić, J., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Bangale, P., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Carmona, E., Carosi, A., Fidalgo, D. Carreto, Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., De Lotto, B., Mendez, C. Delgado, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Eisenacher, D., Elsaesser, D., Farina, E., Ferenc, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Giavitto, G., Godinović, N., Muñoz, A. González, Gozzini, S. R., Hadamek, A., Hadasch, D., Herrero, A., Hildebrand, D., Hose, J., Hrupec, D., Idec, W., Kadenius, V., Kellermann, H., Knoetig, M. L., Krause, J., Kushida, J., La Barbera, A., Lelas, D., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Lozano, I., Makariev, M., Mallot, K., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Meucci, M., Miranda, J. M., Mirzoyan, R., Moralejo, A., Munar-Adrover, P., Nakajima, D., Niedzwiecki, A., Nilsson, K., Nowak, N., Orito, R., Overkemping, A., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Paredes-Fortuny, X., Partini, S., Persic, M., Prada, F., Moroni, P. G. Prada, Prandini, E., Preziuso, S., Puljak, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Garcia, J. Rodriguez, Rügamer, S., Saggion, A., Saito, K., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Stamatescu, V., Stamerra, A., Steinbring, T., Storz, J., Sun, S., Surić, T., Takalo, L., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thaele, J., Tibolla, O., Torres, D. F., Toyama, T., Treves, A., Uellenbeck, M., Vogler, P., Wagner, R. M., Zandanel, F., Zanin, R., Balmaverde, B., Kataoka, J., Rekola, R., and Takahashi, Y.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The radio galaxy NGC 1275, recently identified as a very high energy (VHE, >100 GeV) gamma-ray emitter by MAGIC, is one of the few non-blazar AGN detected in the VHE regime. In order to better understand the origin of the gamma-ray emission and locate it within the galaxy, we studied contemporaneous multi-frequency observations of NGC 1275 and modeled the overall spectral energy distribution (SED). We analyzed unpublished MAGIC observations carried out between Oct. 2009 and Feb. 2010, and the previously published ones taken between Aug. 2010 and Feb. 2011. We studied the multi-band variability and correlations by analyzing data of Fermi-LAT (0.1-100 GeV), as well as Chandra (X-ray), KVA (optical) and MOJAVE (radio) data taken during the same period. Using customized Monte Carlo simulations corresponding to early MAGIC stereo data, we detect NGC 1275 also in the earlier campaign. The flux level and energy spectra are similar to the results of the second campaign. The monthly light curve >100 GeV shows a hint of variability at the 3.6 sigma level. In the Fermi-LAT band, both flux and spectral shape variabilities are reported. The optical light curve is variable and shows a clear correlation with the gamma-ray flux >100 MeV. In radio, 3 compact components are resolved in the innermost part of the jet. One of them shows a similar trend as the LAT and KVA light curves. The 0.1-650 GeV spectra measured simultaneously with MAGIC and Fermi-LAT can be well fitted either by a log-parabola or by a power-law with a sub-exponential cutoff for both campaigns. A single-zone synchrotron-self-Compton model, with an electron spectrum following a power-law with an exponential cutoff, can explain the broadband SED and the multi-band behavior of the source. However, this model suggests an untypical low bulk-Lorentz factor or a velocity alignment closer to the line of sight than the pc-scale radio jet., Comment: 14 pages, 11 figures, accepted for publication in A&A
Published: 2013
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167. The Cherenkov Telescope Array Large Size Telescope

Author: Ambrosi, G., Awane, Y., Baba, H., Bamba, A., Barceló, M., de Almeida, U. Barres, Barrio, J. A., Bigas, O. Blanch, Boix, J., Brunetti, L., Carmona, E., Chabanne, E., Chikawa, M., Colin, P., Conteras, J. L., Cortina, J., Dazzi, F., Deangelis, A., Deleglise, G., Delgado, C., Díaz, C., Dubois, F., Fiasson, A., Fink, D., Fouque, N., Freixas, L., Fruck, C., Gadola, A., García, R., Gascon, D., Geffroy, N., Giglietto, N., Giordano, F., Grañena, F., Gunji, S., Hagiwara, R., Hamer, N., Hanabata, Y., Hassan, T., Hatanaka, K., Haubold, T., Hayashida, M., Hermel, R., Herranz, D., Hirotani, K., Inoue, S., Inoue, Y., Ioka, K., Jablonski, C., Kagaya, M., Katagiri, H., Kishimoto, T., Kodani, K., Kohri, K., Konno, Y., Koyama, S., Kubo, H., Kushida, J., Lamanna, G., Flour, T. Le, López-Moya, M., López, R., Lorenz, E., Majumdar, P., Manalaysay, A., Mariotti, M., Martínez, G., Martínez, M., Mazin, D., Miranda, J. M., Mirzoyan, R., Monteiro, I., Moralejo, A., Murase, K., Nagataki, S., Nakajima, D., Nakamori, T., Nishijima, K., Noda, K., Nozato, A., Ohira, Y., Ohishi, M., Ohoka, H., Okumura, A., Orito, R., Panazol, J. L., Paneque, D., Paoletti, R., Paredes, J. M., Pauletta, G., Podkladkin, S., Prast, J., Rando, R., Reimann, O., Ribó, M., Rosier-Lees, S., Saito, K., Saito, T., Saito, Y., Sakaki, N., Sakonaka, R., Sanuy, A., Sasaki, H., Sawada, M., Scalzotto, V., Schultz, S., Schweizer, T., Shibata, T., Shu, S., Sieiro, J., Stamatescu, V., Steiner, S., Straumann, U., Sugawara, R., Tajima, H., Takami, H., Tanaka, S., Tanaka, M., Tejedor, L. A., Terada, Y., Teshima, M., Totani, T., Ueno, H., Umehara, K., Vollhardt, A., Wagner, R., Wetteskind, H., Yamamoto, T., Yamazaki, R., Yoshida, A., Yoshida, T., and Yoshikoshi, T.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: The two arrays of the Very High Energy gamma-ray observatory Cherenkov Telescope Array (CTA) will include four Large Size Telescopes (LSTs) each with a 23 m diameter dish and 28 m focal distance. These telescopes will enable CTA to achieve a low-energy threshold of 20 GeV, which is critical for important studies in astrophysics, astroparticle physics and cosmology. This work presents the key specifications and performance of the current LST design in the light of the CTA scientific objectives., Comment: 4 pages, 5 figures, In Proceedings of the 33rd International Cosmic Ray Conference (ICRC2013), Rio de Janeiro (Brazil). All CTA contributions at arXiv:1307.2232
Published: 2013

168. The NectarCAM camera project

Author: Glicenstein, J-F., Barcelo, M., Barrio, J-A., Blanch, O., Boix, J., Bolmont, J., Boutonnet, C., Cazaux, S., Chabanne, E., Champion, C., Chateau, F., Colonges, S., Corona, P., Couturier, S., Courty, B., Delagnes, E., Delgado, C., Ernenwein, J-P., Fegan, S., Ferreira, O., Fesquet, M., Fontaine, G., Fouque, N., Henault, F., Gascón, D., Herranz, D., Hermel, R., Hoffmann, D., Houles, J., Karkar, S., Khelifi, B., Knödlseder, J., Martinez, G., Lacombe, K., Lamanna, G., LeFlour, T., Lopez-Coto, R., Louis, F., Mathieu, A., Moulin, E., Nayman, P., Nunio, F., Olive, J-F., Panazol, J-L., Petrucci, P-O., Punch, M., Prast, J., Ramon, P., Riallot, M., Ribó, M., Rosier-Lees, S., Sanuy, A., Siero, J., Tavernet, J-P., Tejedor, L. A., Toussenel, F., Vasileiadis, G., Voisin, V., Waegebert, V., and Zurbach, C.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: In the framework of the next generation of Cherenkov telescopes, the Cherenkov Telescope Array (CTA), NectarCAM is a camera designed for the medium size telescopes covering the central energy range of 100 GeV to 30 TeV. NectarCAM will be finely pixelated (~ 1800 pixels for a 8 degree field of view, FoV) in order to image atmospheric Cherenkov showers by measuring the charge deposited within a few nanoseconds time-window. It will have additional features like the capacity to record the full waveform with GHz sampling for every pixel and to measure event times with nanosecond accuracy. An array of a few tens of medium size telescopes, equipped with NectarCAMs, will achieve up to a factor of ten improvement in sensitivity over existing instruments in the energy range of 100 GeV to 10 TeV. The camera is made of roughly 250 independent read-out modules, each composed of seven photo-multipliers, with their associated high voltage base and control, a read-out board and a multi-service backplane board. The read-out boards use NECTAr (New Electronics for the Cherenkov Telescope Array) ASICs which have the dual functionality of analogue memories and Analogue to Digital Converter (ADC). The camera trigger to be used will be flexible so as to minimize the read-out dead-time of the NECTAr chips. We present the camera concept and the design and tests of the various subcomponents. The design includes the mechanical parts, the cooling of the electronics, the readout, the data acquisition, the trigger, the monitoring and services., Comment: In Proceedings of the 33rd International Cosmic Ray Conference (ICRC2013), Rio de Janeiro (Brazil). All CTA contributions at arXiv:1307.2232
Published: 2013

169. Exploring high-energy processes in binary systems with the Cherenkov Telescope Array

Author: Paredes, J. M., Bednarek, W., Bordas, P., Bosch-Ramon, V., del Pozo, E. De Cea, Dubus, G., Funk, S., Hadasch, D., Khangulyan, D., Markoff, S., Moldon, J., Munar-Adrover, P., Nagataki, S., Naito, T., de Naurois, M., Pedaletti, G., Reimer, O., Ribo, M., Szostek, A., Terada, Y., Torres, D. F., Zabalza, V., and Zdziarski, A. A.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Several types of binary systems have been detected up to now at high and very high gamma-ray energies, including microquasars, young pulsars around massive stars and colliding wind binaries. The study of the sources already known, and of the new types of sources expected to be discovered with the unprecedented sensitivity of CTA, will allow us to qualitatively improve our knowledge on particle acceleration, emission and radiation reprocessing, and on the dynamics of flows and their magnetic fields. Here we present some examples of the capabilities of CTA to probe the flux and spectral changes that typically occur in these astrophysical sources, as well as to search for delays in correlated X-ray/TeV variability with CTA and satellites of the CTA era. Our results show that our knowledge of the high-energy physics in binary systems will significantly deepen with CTA., Comment: In Proceedings of the 33rd International Cosmic Ray Conference (ICRC2013), Rio de Janeiro (Brazil). All CTA contributions at arXiv:1307.2232
Published: 2013

170. CTA contributions to the 33rd International Cosmic Ray Conference (ICRC2013)

Author: Consortium, The CTA, Abril, O., Acharya, B. S., Actis, M., Agnetta, G., Aguilar, J. A., Aharonian, F., Ajello, M., Akhperjanian, A., Alcubierre, M., Aleksic, J., Alfaro, R., Aliu, E., Allafort, A. J., Allan, D., Allekotte, I., Aloisio, R., Amato, E., Ambrosi, G., Ambrosio, M., Anderson, J., Angüner, E. O., Antonelli, L. A., Antonuccio, V., Antonucci, M., Antoranz, P., Aravantinos, A., Argan, A., Arlen, T., Aramo, C., Armstrong, T., Arnaldi, H., Arrabito, L., Asano, K., Ashton, T., Asorey, H. G., Aune, T., Awane, Y., Baba, H., Babic, A., Baby, N., Bähr, J., Bais, A., Baixeras, C., Bajtlik, S., Balbo, M., Balis, D., Balkowski, C., Ballet, J., Bamba, A., Bandiera, R., Barber, A., Barbier, C., Barceló, M., Barnacka, A., Barnstedt, J., de Almeida, U. Barres, Barrio, J. A., Basili, A., Basso, S., Bastieri, D., Bauer, C., Baushev, A., Becciani, U., Becerra, J., Becherini, Y., Bechtol, K. C., Tjus, J. Becker, Beckmann, V., Bednarek, W., Behera, B., Belluso, M., Benbow, W., Berdugo, J., Berge, D., Berger, K., Bernard, F., Bernardino, T., Bernlöhr, K., Bertucci, B., Bhat, N., Bhattacharyya, S., Biasuzzi, B., Bigongiari, C., Biland, A., Billotta, S., Bird, T., Birsin, E., Bissaldi, E., Biteau, J., Bitossi, M., Blake, S., Bigas, O. Blanch, Blasi, P., Bobkov, A., Boccone, V., Böttcher, M., Bogacz, L., Bogart, J., Bogdan, M., Boisson, C., Gargallo, J. Boix, Bolmont, J., Bonanno, G., Bonardi, A., Bonev, T., Bonifacio, P., Bonnoli, G., Bordas, P., Borgland, A., Borkowski, J., Bose, R., Botner, O., Bottani, A., Bouchet, L., Bourgeat, M., Boutonnet, C., Bouvier, A., Brau-Nogué, S., Braun, I., Bretz, T., Briggs, M., Brigida, M., Bringmann, T., Britto, R., Brook, P., Brun, P., Brunetti, L., Bruno, P., Bucciantini, N., Buanes, T., Buckley, J., Bühler, R., Bugaev, V., Bulgarelli, A., Bulik, T., Busetto, G., Buson, S., Byrum, K., Cailles, M., Cameron, R., Camprecios, J., Canestrari, R., Cantu, S., Capalbi, M., Caraveo, P., Carmona, E., Carosi, A., Carosi, R., Carr, J., Carter, J., Carton, P. -H., Caruso, R., Casanova, S., Cascone, E., Casiraghi, M., Castellina, A., Catalano, O., Cavazzani, S., Cazaux, S., Cerchiara, P., Cerruti, M., Chabanne, E., Chadwick, P., Champion, C., Chaves, R., Cheimets, P., Chen, A., Chiang, J., Chiappetti, L., Chikawa, M., Chitnis, V. R., Chollet, F., Christof, A., Chudoba, J., Cieślar, M., Cillis, A., Cilmo, M., Codino, A., Cohen-Tanugi, J., Colafrancesco, S., Colin, P., Colome, J., Colonges, S., Compin, M., Conconi, P., Conforti, V., Connaughton, V., Conrad, J., Contreras, J. L., Coppi, P., Coridian, J., Corona, P., Corti, D., Cortina, J., Cossio, L., Costa, A., Costantini, H., Cotter, G., Courty, B., Couturier, S., Covino, S., Crimi, G., Criswell, S. J., Croston, J., Cusumano, G., Dafonseca, M., Dale, O., Daniel, M., Darling, J., Davids, I., Dazzi, F., de Angelis, A., De Caprio, V., De Frondat, F., Pino, E. M. de Gouveia Dal, de la Calle, I., De La Vega, G. 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J., Wierzcholska, A., Wiesand, S., Wilhelm, A., Wilkinson, M. I., Williams, D. A., Willingale, R., Winde, M., Winiarski, K., Wischnewski, R., Wiśniewski, Ł., Wojcik, P., Wood, M., Wörnlein, A., Xiong, Q., Yadav, K. K., Yamamoto, H., Yamamoto, T., Yamazaki, R., Yanagita, S., Yebras, J. M., Yelos, D., Yoshida, A., Yoshida, T., Yoshikoshi, T., Yu, P., Zabalza, V., Zacharias, M., Zajczyk, A., Zampieri, L., Zanin, R., Zdziarski, A., Zech, A., Zhao, A., Zhou, X., Zietara, K., Ziolkowski, J., Ziółkowski, P., Zitelli, V., Zurbach, C., and Zychowski, P.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, High Energy Physics - Experiment
Abstract: Compilation of CTA contributions to the proceedings of the 33rd International Cosmic Ray Conference (ICRC2013), which took place in 2-9 July, 2013, in Rio de Janeiro, Brazil, Comment: Index of CTA conference proceedings at the ICRC2013, Rio de Janeiro (Brazil). v1: placeholder with no arXiv links yet, to be replaced once individual contributions have been all submitted. v2: final with arXiv links to all CTA contributions and full author list
Published: 2013

171. Rapid and multi-band variability of the TeV-bright active nucleus of the galaxy IC 310

Author: The MAGIC Collaboration, Aleksić, J., Antonelli, L. A., Antoranz, P., Babic, A., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnefoy, S., Bonnoli, G., Tridon, D. Borla, Borracci, F., Bretz, T., Carmona, E., Carosi, A., Fidalgo, D. Carreto, Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., Mendez, C. Delgado, De Lotto, B., Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Eisenacher, D., Elsaesser, D., Farina, E., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Giavitto, G., Godinović, N., Muñoz, A. González, Gozzini, S. R., Hadamek, A., Hadasch, D., Häfner, D., Herrero, A., Hose, J., Hrupec, D., Idec, W., Kadenius, V., Knoetig, M. L., Krähenbühl, T., Krause, J., Kushida, J., La Barbera, A., Lelas, D., Lewandowska, N., Lindfors, E., Lombardi, S., López-Coto, R., López, M., López-Oramas, A., Lorenz, E., Lozano, I., Makariev, M., Mallot, K., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Masbou, J., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Moldón, J., Moralejo, A., Munar-Adrover, P., Nakajima, D., Niedzwiecki, A., Nilsson, K., Nowak, N., Orito, R., Overkemping, A., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Partini, S., Persic, M., Prada, F., Moroni, P. G. Prada, Prandini, E., Preziuso, S., Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rügamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Spiro, S., Stamatescu, V., Stamerra, A., Steinke, B., Storz, J., Sun, S., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thaele, J., Tibolla, O., Torres, D. F., Toyama, T., Treves, A., Uellenbeck, M., Vogler, P., Wagner, R. M., Weitzel, Q., Zandanel, F., Zanin, R., Dauser, T., Fortin, P., Kadler, M., Krauß, F., Wilbert, S., and Wilms, J.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Context. The radio galaxy IC 310 has recently been identified as a gamma-ray emitter based on observations at GeV energies with Fermi-LAT and at very high energies (VHE, E>100GeV) with the MAGIC telescopes. Originally classified as a head-tail radio galaxy, the nature of this object is subject of controversy since its nucleus shows blazar-like behavior. Aims. In order to understand the nature of IC 310 and the origin of the VHE emission we studied the spectral and flux variability of IC 310 from the X-ray band to the VHE gamma-ray regime. Methods. The light curve of IC 310 above 300GeV has been measured with the MAGIC telescopes from Oct. 2009 to Feb. 2010. Fermi-LAT data (2008-2011) in the 10-500GeV energy range were also analyzed. In X-ray, archival observations from 2003 to 2007 with XMM, Chandra, and Swift-XRT in the 0.5-10keV band were studied. Results. The VHE light curve reveals several high-amplitude and short-duration flares. Day-to-day flux variability is clearly present. The photon index between 120GeV and 8TeV remains at the value $\Gamma\sim2.0$ during both low and high flux states. The VHE spectral shape does not show significant variability, whereas the flux at 1TeV changes by a factor of $\sim7$. Fermi-LAT detected only eight gamma-ray events in the energy range 10GeV-500GeV in three years of observation. The measured photon index of $\Gamma=1.3\pm0.5$ in the Fermi-LAT range is very hard. The X-ray measurements show strong variability in flux and photon index. The latter varied from $1.76\pm0.07$ to $2.55\pm0.07$. Conclusion. The rapid variability measured confirms the blazar-like behavior of IC 310. The TeV emission seems to originate from scales of less than 80 Schwarzschild radii within the compact core of its FRI radio jet with orientation angle 10deg-38deg. The SED resembles that of an extreme blazar, albeit the luminosity is more than two orders of magnitude lower., Comment: 9 pages, 5 figures, 4 tables. Accepted for publication in A&A
Published: 2013
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172. Discovery of very high energy gamma-ray emission from the blazar 1ES 1727+502 with the MAGIC Telescopes

Author: MAGIC Collaboration, Aleksić, J., Antonelli, L. A., Antoranz, P., Asensio, M., Backes, M., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnefoy, S., Bonnoli, G., Tridon, D. Borla, Borracci, F., Bretz, T., Carmona, E., Carosi, A., Fidalgo, D. Carreto, Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., De Lotto, B., Mendez, C. Delgado, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Eisenacher, D., Elsaesser, D., Farina, E., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Giavitto, G., Godinović, N., Muñoz, A. González, Gozzini, S. R., Hadamek, A., Hadasch, D., Häfner, D., Herrero, A., Hose, J., Hrupec, D., Idec, W., Jankowski, F., Kadenius, V., Klepser, S., Knoetig, M. L., Krähenbühl, T., Krause, J., Kushida, J., La Barbera, A., Lelas, D., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Lozano, I., Makariev, M., Mallot, K., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Masbou, J., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Moldón, J., Moralejo, A., Munar-Adrover, P., Nakajima, D., Niedzwiecki, A., Nilsson, K., Nowak, N., Orito, R., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Partini, S., Persic, M., Prada, F., Moroni, P. G. Prada, Prandini, E., Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rügamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Spiro, S., Stamatescu, V., Stamerra, A., Steinke, B., Storz, J., Sun, S., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Tibolla, O., Torres, D. F., Toyama, T., Treves, A., Uellenbeck, M., Vogler, P., Wagner, R. M., Weitzel, Q., Zandanel, F., and Zanin, R.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Motivated by the Costamante & Ghisellini (2002) predictions we investigated if the blazar 1ES 1727+502 (z=0.055) is emitting very high energy (VHE, E>100 GeV) gamma rays. We observed the BL Lac object 1ES 1727+502 in stereoscopic mode with the two MAGIC telescopes during 14 nights between May 6th and June 10th 2011, for a total effective observing time of 12.6 hours. For the study of the multiwavelength spectral energy distribution (SED) we use simultaneous optical R-band data from the KVA telescope, archival UV/optical and X-ray observations by instruments UVOT and XRT on board of the Swift satellite and high energy (HE, 0.1 GeV - 100 GeV) gamma-ray data from the Fermi-LAT instrument. We detect, for the first time, VHE gamma-ray emission from 1ES 1727+502 at a statistical significance of 5.5 sigma. The integral flux above 150 GeV is estimated to be (2.1\pm0.4)% of the Crab Nebula flux and the de-absorbed VHE spectrum has a photon index of (2.7\pm0.5). No significant short-term variability was found in any of the wavebands presented here. We model the SED using a one-zone synchrotron self-Compton model obtaining parameters typical for this class of sources., Comment: 7 pages, 5 figures, 2 tables, submitted to A&A
Published: 2013
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173. Penumbral imaging and functional outcome in patients with anterior circulation ischaemic stroke treated with endovascular thrombectomy versus medical therapy: a meta-analysis of individual patient-level data

Author: Berkhemer, Olvert A, Fransen, Puck SS, Beumer, Debbie, van den Berg, Lucie A, Lingsma, Hester F, Yoo, Albert J, Schonewille, Wouter J, Vos, Jan Albert, Nederkoorn, Paul J, Wermer, Marieke JH, van Walderveen, Marianne AA, Staals, Julie, Hofmeijer, Jeannette, van Oostayen, Jacques A., Lycklama à Nijeholt, Geert J., Boiten, Jelis, Brouwer, Patrick A., Emmer, Bart J., de Bruijn, Sebastiaan F., van Dijk, Lukas C., Kappelle, Jaap, Lo, Rob H, van Dijk, Ewoud J., de Vries, Joost, de Kort, Paul L.M., van Rooij, Willem Jan J., van den Berg, Jan S.P., van Hasselt, Boudewijn A.A.M., Aerden, Leo A.M., Dallinga, René J., Visser, Marieke C., Bot, Joseph C.J., Vroomen, Patrick C., Eshghi, Omid, Schreuder, Tobien H.C.M.L., Heijboer, Roel J.J., Keizer, Koos, Tielbeek, Alexander V., den Hertog, Heleen M., Gerrits, Dick G., van den Berg-Vos, Renske M., Karas, Giorgos B., Steyerberg, Ewout W., Flach, Zwenneke, Marquering, Henk A., Sprengers, Marieke E.S., Jenniskens, Sjoerd F.M., Beenen, Ludo F.M., van den Berg, René, Koudstaal, Peter J., van Zwam, Wim H., Roos, Yvo B.W.E.M., van der Lugt, Aad, van Oostenbrugge, Robert J., Majoie, Charles B.L.M., Dippel, Diederik W.J., Brown, Martin M., Liebig, Thomas, Stijnen, Theo, Andersson, Tommy, Mattle, Heinrich, Wahlgren, Nils, van der Heijden, Esther, Ghannouti, Naziha, Fleitour, Nadine, Hooijenga, Imke, Puppels, Corina, Pellikaan, Wilma, Geerling, Annet, Lindl-Velema, Annemieke, van Vemde, Gina, de Ridder, Ans, Greebe, Paut, de Bont-Stikkelbroeck, José, de Meris, Joke, Janssen, Kirsten, Struijk, Willy, Licher, Silvan, Boodt, Nikki, Ros, Adriaan, Venema, Esmee, Slokkers, Ilse, Ganpat, Raymie-Jayce, Mulder, Maxim, Saiedie, Nawid, Heshmatollah, Alis, Schipperen, Stefanie, Vinken, Stefan, van Boxtel, Tiemen, Koets, Jeroen, Boers, Merel, Santos, Emilie, Borst, Jordi, Jansen, Ivo, Kappelhof, Manon, Lucas, Marit, Geuskens, Ralph, Barros, Renan Sales, Dobbe, Roeland, Csizmadia, Marloes, Hill, MD, Goyal, M, Demchuk, AM, Menon, BK, Eesa, M, Ryckborst, KJ, Wright, MR, Kamal, NR, Andersen, L, Randhawa, PA, Stewart, T, Patil, S, Minhas, P, Almekhlafi, M, Mishra, S, Clement, F, Sajobi, T, Shuaib, A, Montanera, WJ, Roy, D, Silver, FL, Jovin, TG, Frei, DF, Sapkota, B, Rempel, JL, Thornton, J, Williams, D, Tampieri, D, Poppe, AY, Dowlatshahi, D, Wong, JH, Mitha, AP, Subramaniam, S, Hull, G, Lowerison, MW, Salluzzi, M, Maxwell, M, Lacusta, S, Drupals, E, Armitage, K, Barber, PA, Smith, EE, Morrish, WF, Coutts, SB, Derdeyn, C, Demaerschalk, B, Yavagal, D, Martin, R, Brant, R, Yu, Y, Willinsky, RA, Weill, A, Kenney, C, Aram, H, Stys, PK, Watson, TW, Klein, G, Pearson, D, Couillard, P, Trivedi, A, Singh, D, Klourfeld, E, Imoukhuede, O, Nikneshan, D, Blayney, S, Reddy, R, Choi, P, Horton, M, Musuka, T, Dubuc, V, Field, TS, Desai, J, Adatia, S, Alseraya, A, Nambiar, V, van Dijk, R, Newcommon, NJ, Schwindt, B, Butcher, KS, Jeerakathil, T, Buck, B, Khan, K, Naik, SS, Emery, DJ, Owen, RJ, Kotylak, TB, Ashforth, RA, Yeo, TA, McNally, D, Siddiqui, M, Saqqur, M, Hussain, D, Kalashyan, H, Manosalva, A, Kate, M, Gioia, L, Hasan, S, Mohammad, A, Muratoglu, M, Cullen, A, Brennan, P, O'Hare, A, Looby, S, Hyland, D, Duff, S, McCusker, M, Hallinan, B, Lee, S, McCormack, J, Moore, A, O'Connor, M, Donegan, C, Brewer, L, Martin, A, Murphy, S, O'Rourke, K, Smyth, S, Kelly, P, Lynch, T, Daly, T, O'Brien, P, O'Driscoll, A, Martin, M, Collins, R, Coughlan, T, McCabe, D, O'Neill, D, Mulroy, M, Lynch, O, Walsh, T, O'Donnell, M, Galvin, T, Harbison, J, McElwaine, P, Mulpeter, K, McLoughlin, C, Reardon, M, Harkin, E, Dolan, E, Watts, M, Cunningham, N, Fallon, C, Gallagher, S, Cotter, P, Crowe, M, Doyle, R, Noone, I, Lapierre, M, Coté, VA, Lanthier, S, Odier, C, Durocher, A, Raymond, J, Daneault, N, Deschaintre, Y, Jankowitz, B, Baxendell, L, Massaro, L, Jackson-Graves, C, Decesare, S, Porter, P, Armbruster, K, Adams, A, Billigan, J, Oakley, J, Ducruet, A, Jadhav, A, Giurgiutiu, D-V, Aghaebrahim, A, Reddy, V, Hammer, M, Starr, M, 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Claire, Daumas-Duport, Benjamin, De Gaalon, Solène, Derkinderen, Pascal, Evain, Sarah, Herisson, Fanny, Laplaud, David-Axel, Lebouvier, Thibaud, Lintia-Gaultier, Alina, Pouclet-Courtemanche, Hélène, Rouaud, Tiphaine, Rouaud Jaffrenou, Violaine, Schunck, Aurélia, Sevin-Allouet, Mathieu, Toulgoat, Frederique, Wiertlewski, Sandrine, Gauvrit, Jean-Yves, Ronziere, Thomas, Cahagne, Vincent, Ferre, Jean-Christophe, Pinel, Jean-François, Raoult, Hélène, Mas, Jean-Louis, Meder, Jean-François, Al Najjar-Carpentier, Amen-Adam, Birchenall, Julia, Bodiguel, Eric, Calvet, David, Domigo, Valérie, Godon-Hardy, Sylvie, Guiraud, Vincent, Lamy, Catherine, Majhadi, Loubna, Morin, Ludovic, Naggara, Olivier, Trystram, Denis, Turc, Guillaume, Berge, Jérôme, Sibon, Igor, Menegon, Patrice, Barreau, Xavier, Rouanet, François, Debruxelles, Sabrina, Kazadi, Annabelle, Renou, Pauline, Fleury, Olivier, Pasco-Papon, Anne, Dubas, Frédéric, Caroff, Jildaz, Godard Ducceschi, Sophie, Hamon, Marie-Aurélie, Lecluse, Alderic, Marc, Guillaume, Giroud, Maurice, Ricolfi, Frédéric, Bejot, Yannick, Chavent, Adrien, Gentil, Arnaud, Kazemi, Apolline, Osseby, Guy-Victor, Voguet, Charlotte, Mahagne, Marie-Hélène, Sedat, Jacques, Chau, Yves, Suissa, Laurent, Lachaud, Sylvain, Houdart, Emmanuel, Stapf, Christian, Buffon Porcher, Frédérique, Chabriat, Hugues, Guedin, Pierre, Herve, Dominique, Jouvent, Eric, Mawet, Jérôme, Saint-Maurice, Jean-Pierre, Schneble, Hans-Martin, Nighoghossian, Norbert, Berhoune, Nadia-Nawel, Bouhour, Françoise, Cho, Tae-Hee, Derex, Laurent, Felix, Sandra, Gervais-Bernard, Hélène, Gory, Benjamin, Manera, Luis, Mechtouff, Laura, Ritzenthaler, Thomas, Riva, Roberto, Salaris Silvio, Fabrizio, Tilikete, Caroline, Blanc, Raphael, Obadia, Michaël, Bartolini, Mario Bruno, Gueguen, Antoine, Piotin, Michel, Pistocchi, Silvia, Redjem, Hocine, Drouineau, Jacques, Neau, Jean-Philippe, Godeneche, Gaelle, Lamy, Matthias, Marsac, Emilia, Velasco, Stephane, Clavelou, Pierre, Chabert, Emmanuel, Bourgois, Nathalie, Cornut-Chauvinc, Catherine, Ferrier, Anna, Gabrillargues, Jean, Jean, Betty, Marques, Anna-Raquel, Vitello, Nicolas, Detante, Olivier, Barbieux, Marianne, Boubagra, Kamel, Favre Wiki, Isabelle, Garambois, Katia, Tahon, Florence, Ashok, Vasdev, Coskun, Oguzhan, Rodesch, Georges, Lapergue, Bertrand, Bourdain, Frédéric, Evrard, Serge, Graveleau, Philippe, Decroix, Jean Pierre, Wang, Adrien, Sellal, François, Ahle, Guido, Carelli, Gabriela, Dugay, Marie-Hélène, Gaultier, Claude, Lebedinsky, Ariel Pablo, Lita, Lavinia, Musacchio, Raul Mariano, Renglewicz-Destuynder, Catherine, Tournade, Alain, Vuillemet, Françis, Montoro, Francisco Macian, Mounayer, Charbel, Faugeras, Frederic, Gimenez, Laetitia, Labach, Catherine, Lautrette, Géraldine, Denier, Christian, Saliou, Guillaume, Chassin, Olivier, Dussaule, Claire, Melki, Elsa, Ozanne, Augustin, Puccinelli, Francesco, Sachet, Marina, Sarov, Mariana, Bonneville, Jean-François, Moulin, Thierry, Biondi, Alessandra, De Bustos Medeiros, Elisabeth, Vuillier, Fabrice, Courtheoux, Patrick, Viader, Fausto, Apoil-Brissard, Marion, Bataille, Mathieu, Bonnet, Anne-Laure, Cogez, Julien, Touze, Emmanuel, Leclerc, Xavier, Leys, Didier, Aggour, Mohamed, Aguettaz, Pierre, Bodenant, Marie, Cordonnier, Charlotte, Deplanque, Dominique, Girot, Marie, Henon, Hilde, Kalsoum, Erwah, Lucas, Christian, Pruvo, Jean-Pierre, Zuniga, Paolo, Arquizan, Caroline, Costalat, Vincent, Machi, Paolo, Mourand, Isabelle, Riquelme, Carlos, Bounolleau, Pierre, Arteaga, Charles, Faivre, Anthony, Bintner, Marc, Tournebize, Patrice, Charlin, Cyril, Darcel, Françoise, Gauthier-Lasalarie, Pascale, Jeremenko, Marcia, Mouton, Servane, Zerlauth, Jean-Baptiste, Lamy, Chantal, Hervé, Deramond, Hassan, Hosseini, Gaston, André, Barral, Francis-Guy, Garnier, Pierre, Beaujeux, Rémy, Wolff, Valérie, Herbreteau, Denis, Debiais, Séverine, Murray, Alicia, Ford, Gary, Muir, Keith W, White, Philip, Clifton, Andy, Freeman, Janet, Ford, Ian, Markus, Hugh, Wardlaw, Joanna, Molyneux, Andy, Robinson, Thompson, Lewis, Steff, Norrie, John, Robertson, Fergus, Perry, Richard, Dixit, Anand, Cloud, Geoffrey, Clifton, Andrew, Madigan, Jeremy, Roffe, Christine, Nayak, Sanjeev, Lobotesis, Kyriakos, Smith, Craig, Herwadkar, Amit, Kandasamy, Naga, Goddard, Tony, Bamford, John, Subramanian, Ganesh, Lenthall, Rob, Littleton, Edward, Lamin, Sal, Storey, Kelley, Ghatala, Rita, Banaras, Azra, Aeron-Thomas, John, Hazel, Bath, Maguire, Holly, Veraque, Emelda, Harrison, Louise, Keshvara, Rekha, Cunningham, James, Campbell, Bruce C V, Majoie, Charles B L M, Menon, Bijoy K, van Zwam, Wim H, van Oostenbrugge, Robert J, Demchuk, Andrew M, Guillemin, Francis, Dávalos, Antoni, Butcher, Kenneth S, Cherifi, Aboubaker, Marquering, Henk A, Macho Fernández, Juan M, Oppenheim, Catherine, Roos, Yvo B W E M, Shankar, Jai, Lingsma, Hester, Hernández-Pérez, María, Bharatha, Aditya, Levy, Elad I, Soudant, Marc, Aja, Lucia, Krings, Timo, Tisserand, Marie, San Román, Luis, Tomasello, Alejandro, Brown, Scott, Liebeskind, David S, Bracard, Serge, Dippel, Diederik W J, Jovin, Tudor G, and Hill, Michael D
Published: 2019
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174. The Simultaneous Low State Spectral Energy Distribution of 1ES 2344+514 from Radio to Very High Energies

Author: MAGIC Collaboration, Aleksić, J., Antonelli, L. A., Antoranz, P., Asensio, M., Backes, M., de Almeida, U. Barres, Barrio, J. A., Bednarek, W., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnefoy, S., Bonnoli, G., Tridon, D. Borla, Bretz, T., Carmona, E., Carosi, A., Fidalgo, D. Carreto, Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., De Lotto, B., Mendez, C. Delgado, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Eisenacher, D., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Giavitto, G., Godinović, N., Muñoz, A. González, Gozzini, S. R., Hadamek, A., Hadasch, D., Herrero, A., Hose, J., Hrupec, D., Jankowski, F., Kadenius, V., Klepser, S., Knoetig, M. L., Krähenbühl, T., Krause, J., Kushida, J., La Barbera, A., Lelas, D., Leonardo, E., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Lozano, I., Makariev, M., Mallot, K., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Masbou, J., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Moldón, J., Moralejo, A., Munar-Adrover, P., Nakajima, D., Niedzwiecki, A., Nieto, D., Nilsson, K., Nowak, N., Orito, R., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Partini, S., Persic, M., Pilia, M., Prada, F., Moroni, P. G. Prada, Prandini, E., Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rügamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Spiro, S., Stamatescu, V., Stamerra, A., Steinke, B., Storz, J., Sun, S., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Tibolla, O., Torres, D. F., Toyama, T., Treves, A., Uellenbeck, M., Vogler, P., Wagner, R. M., Weitzel, Q., Zandanel, F., Zanin, R., Collaboration, The MAGIC, Longo, F., Lucarelli, F., Pittori, C., Vercellone, S., Bastieri, D., Sbarra, C., Angelakis, E., Fuhrmann, L., Nestoras, I., Krichbaum, T. P., Sievers, A., Zensus, J. A., Antonyuk, K. A., Baumgartner, W., Berduygin, A., Carini, M., Cook, K., Gehrels, N., Kadler, M., Kovalev, Yu. A., Kovalev, Y. Y., Krauss, F., Krimm, H. A., Lähteenmäki, A., Lister, M. L., Max-Moerbeck, W., Pasanen, M., Pushkarev, A. B., Readhead, A. C. S., Richards, J. L., Sainio, J., Shakhovskoy, D. N., Sokolovsky, K. V., Tornikoski, M., Tueller, J., Weidinger, M., and Wilms, J.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: [Abridged] Context. To construct and interpret the spectral energy distribution (SED) of BL Lacertae objects, simultaneous broad-band observations are mandatory. Aims. We present the results of a dedicated multi-wavelength study of the high-frequency peaked BL Lacertae (HBL) object and known TeV emitter 1ES 2344+514 by means of a pre-organised campaign. Methods. The observations were conducted during simultaneous visibility windows of MAGIC and AGILE in late 2008. The measurements were complemented by Mets\"ahovi, RATAN-600, KVA+Tuorla, Swift and VLBA pointings. Additional coverage was provided by the ongoing long-term F-GAMMA and MOJAVE programs, the OVRO 40-m and CrAO telescopes as well as the Fermi satellite. The obtained SEDs are modelled using a one-zone as well as a self-consistent two-zone synchrotron self-Compton model. Results. 1ES 2344+514 was found at very low flux states in both X-rays and very high energy gamma rays. Variability was detected in the low frequency radio and X-ray bands only, where for the latter a small flare was observed. The X-ray flare was possibly caused by shock acceleration characterised by similar cooling and acceleration time scales. MOJAVE VLBA monitoring reveals a static jet whose components are stable over time scales of eleven years, contrary to previous findings. There appears to be no significant correlation between the 15 GHz and R-band monitoring light curves. The observations presented here constitute the first multi-wavelength campaign on 1ES 2344+514 from radio to VHE energies and one of the few simultaneous SEDs during low activity states. The quasi-simultaneous Fermi-LAT data poses some challenges for SED modelling, but in general the SEDs are described well by both applied models. The resulting parameters are typical for TeV emitting HBLs. Consequently it remains unclear whether a so-called quiescent state was found in this campaign., Comment: 29 pages, 20 figures, 10 tables, accepted for publication by A&A
Published: 2012
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175. Observations of the magnetars 4U 0142+61 and 1E 2259+586 with the MAGIC telescopes

Author: The MAGIC Collaboration, Aleksić, J., Antonelli, L. A., Antoranz, P., Asensio, M., de Almeida, U. Barres, Barrio, J. A., Bednarek, W., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnefoy, S., Bonnoli, G., Tridon, D. Borla, Bretz, T., Carmona, E., Carosi, A., Fidalgo, D. Carreto, Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., De Lotto, B., Mendez, C. Delgado, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Eisenacher, D., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Giavitto, G., Godinović, N., Muñoz, A. González, Gozzini, S. R., Hadamek, A., Hadasch, D., Herrero, A., Hose, J., Hrupec, D., Jankowski, F., Kadenius, V., Klepser, S., Knoetig, M. L., Krähenbühl, T., Krause, J., Kushida, J., La Barbera, A., Lelas, D., Leonardo, E., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Lozano, I., Makariev, M., Mallot, K., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Masbou, J., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Moldón, J., Moralejo, A., Munar-Adrover, P., Nakajima, D., Niedzwiecki, A., Nieto, D., Nilsson, K., Nowak, N., Orito, R., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Partini, S., Persic, M., Pilia, M., Prada, F., Moroni, P. G. Prada, Prandini, E., Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rügamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Spiro, S., Stamatescu, V., Stamerra, A., Steinke, B., Storz, J., Sun, S., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Tibolla, O., Torres, D. F., Toyama, T., Treves, A., Uellenbeck, M., Vogler, P., Wagner, R. M., Weitzel, Q., Zandanel, F., Zanin, R., and Rea, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
Abstract: Magnetars are an extreme, highly magnetized class of isolated neutron stars whose large X-ray luminosity is believed to be driven by their high magnetic field. In this work we study for the first time the possible very high energy gamma-ray emission above 100 GeV from magnetars, observing the sources 4U 0142+61 and 1E 2259+586. We observed the two sources with atmospheric Cherenkov telescopes in the very high energy range (E > 100 GeV). 4U 0142+61 was observed with the MAGIC I telescope in 2008 for ~25 h and 1E 2259+586 was observed with the MAGIC stereoscopic system in 2010 for ~14 h. The data were analyzed with the standard MAGIC analysis software. Neither magnetar was detected. Upper limits to the differential and integral flux above 200 GeV were computed using the Rolke algorithm. We obtain integral upper limits to the flux of 1.52*10^-12cm^-2 s^-1 and 2.7*10^-12cm^-2 s^-1 with a confidence level of 95% for 4U 0142+61 and 1E 2259+586, respectively. The resulting differential upper limits are presented together with X-ray data and upper limits in the GeV energy range., Comment: minor corrections, references updated
Published: 2012
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176. Periodic morphological changes in gamma-ray binaries

Author: Moldón, J., Ribó, M., and Paredes, J. M.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Gamma-ray binaries allow us to study physical processes such as particle acceleration up to very-high energies and gamma-ray emission and absorption with changing geometrical configurations on a periodic basis. They produce outflows of radio-emitting particles whose structure can be imaged with Very Long Baseline Interferometry (VLBI). We present recent and new VLBI observations of PSR B1259-63, LS 5039, LS I +61 303, and HESS J0632+057. For the first three cases the results show the repeatability of their radio structures with the orbit of the binary system., Comment: 4 pages. Proceedings of the "5th International Symposium on High-Energy Gamma-Ray Astronomy", Heidelberg (Germany), 9-13 July 2012
Published: 2012
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177. Binaries with the eyes of CTA

Author: Paredes, J. M., Bednarek, W., Bordas, P., Bosch-Ramon, V., del Pozo, E. De Cea, Dubus, G., Funk, S., Hadasch, D., Khangulyan, D., Markoff, S., Moldon, J., Munar-Adrover, P., Nagataki, S., Naito, T., de Naurois, M., Pedaletti, G., Reimer, O., Ribo, M., Szostek, A., Terada, Y., Torres, D. F., Zabalza, V., and Zdziarski, A. A.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The binary systems that have been detected in gamma rays have proven very useful to study high-energy processes, in particular particle acceleration, emission and radiation reprocessing, and the dynamics of the underlying magnetized flows. Binary systems, either detected or potential gamma-ray emitters, can be grouped in different subclasses depending on the nature of the binary components or the origin of the particle acceleration: the interaction of the winds of either a pulsar and a massive star or two massive stars; accretion onto a compact object and jet formation; and interaction of a relativistic outflow with the external medium. We evaluate the potentialities of an instrument like the Cherenkov telescope array (CTA) to study the non-thermal physics of gamma-ray binaries, which requires the observation of high-energy phenomena at different time and spatial scales. We analyze the capability of CTA, under different configurations, to probe the spectral, temporal and spatial behavior of gamma-ray binaries in the context of the known or expected physics of these sources. CTA will be able to probe with high spectral, temporal and spatial resolution the physical processes behind the gamma-ray emission in binaries, significantly increasing as well the number of known sources. This will allow the derivation of information on the particle acceleration and emission sites qualitatively better than what is currently available., Comment: 23 pages, 13 figures, accepted for publication in Astroparticle Physics, special issue on Physics with the Cherenkov Telescope Array
Published: 2012
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178. Periodic morphological changes in the radio structure of the gamma-ray binary LS 5039

Author: Moldón, J., Ribó, M., and Paredes, J. M.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Gamma-ray binaries allow us to study physical processes such as particle acceleration up to TeV energies and VHE gamma-ray emission and absorption with changing geometrical configurations on a periodic basis. These sources produce outflows of radio-emitting particles whose structure can be imaged with VLBI. LS 5039 is a gamma-ray binary that has shown variable VLBI structures in the past. We aim to characterise the radio morphological changes of LS 5039 and discriminate if they are either repeatable or erratic. We observed LS 5039 with the VLBA at 5 GHz during five consecutive days to cover the 3.9-day orbit and an extra day to disentangle between orbital or secular variability. We also compiled the available high-resolution radio observations of the source to study its morphological variability at different orbital phases. We used a simple model to interpret the obtained images. The new observations show that the morphology of LS 5039 up to projected distances of 10 milliarcseconds changes in 24 h. The observed radio morphological changes display a periodic orbital modulation. Multifrequency and multiepoch VLBI observations confirm that the morphological periodicity is stable on timescales of years. Using a simple model we show that the observed behaviour is compatible with the presence of a young non-accreting pulsar with an outflow behind it. The morphology is reproduced for inclinations of the orbit of 60-75 deg. For masses of the companion star in the range 20-50 Msun, this range of inclinations implies a mass of the compact object of 1.3-2.7 Msun. The periodic orbital modulation of the radio morphology of LS 5039 suggests that all gamma-ray binaries are expected to show a similar behaviour. The changes in the radio structure of LS 5039 are compatible with the presence of a young non-accreting neutron star, which suggests that the known gamma-ray binaries contain young pulsars., Comment: 15 pages, 7 figures. Accepted for publication in Astronomy and Astrophysics
Published: 2012
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179. MAGIC observations of the giant radio galaxy M87 in a low-emission state between 2005 and 2007

Author: MAGIC Collaboration, Aleksić, J., Alvarez, E. A., Antonelli, L. A., Antoranz, P., Asensio, M., Backes, M., Barrio, J. A., Bastieri, D., González, J. Becerra, Bednarek, W., Berdyugin, A., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnoli, G., Tridon, D. Borla, Braun, I., Bretz, T., Cañellas, A., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Dazzi, F., De Angelis, A., De Caneva, G., del Pozo, E. De Cea, De Lotto, B., Mendez, C. Delgado, Ortega, A. Diago, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., López, R. J. García, Garczarczyk, M., Garrido, D., Gaug, M., Giavitto, G., Godinović, N., Hadasch, D., Häfner, D., Herrero, A., Hildebrand, D., Höhne-Mönch, D., Hose, J., Hrupec, D., Huber, B., Jogler, T., Kellermann, H., Klepser, S., Krähenbühl, T., Krause, J., La Barbera, A., Lelas, D., Leonardo, E., Lindfors, E., Lombardi, S., López, M., López-Oramas, A., Lorenz, E., Makariev, M., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Miyamoto, H., Moldón, J., Moralejo, A., Munar-Adrover, P., Nieto, D., Nilsson, K., Orito, R., Oya, I., Paneque, D., Paoletti, R., Pardo, S., Paredes, J. M., Partini, S., Pasanen, M., Pauss, F., Perez-Torres, M. A., Persic, M., Peruzzo, L., Pilia, M., Pochon, J., Prada, F., Moroni, P. G. Prada, Prandini, E., Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rügamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shayduk, M., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Spiro, S., Stamatescu, V., Stamerra, A., Steinke, B., Storz, J., Strah, N., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Tibolla, O., Torres, D. F., Treves, A., Uellenbeck, M., Vankov, H., Vogler, P., Wagner, R. M., Weitzel, Q., Zabalza, V., Zandanel, F., Zanin, R., and Ghisellini, G.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Extragalactic Astrophysics
Abstract: We present the results of a long M87 monitoring campaign in very high energy $\gamma$-rays with the MAGIC-I Cherenkov telescope. We aim to model the persistent non-thermal jet emission by monitoring and characterizing the very high energy $\gamma$-ray emission of M87 during a low state. A total of 150\,h of data were taken between 2005 and 2007 with the single MAGIC-I telescope, out of which 128.6\,h survived the data quality selection. We also collected data in the X-ray and \textit{Fermi}--LAT bands from the literature (partially contemporaneous). No flaring activity was found during the campaign. The source was found to be in a persistent low-emission state, which was at a confidence level of $7\sigma$. We present the spectrum between 100\,GeV and 2\,TeV, which is consistent with a simple power law with a photon index $\Gamma=2.21\pm0.21$ and a flux normalization at 300\,GeV of $(7.7\pm1.3) \times 10^{-8}$ TeV$^{-1}$ s$^{-1}$ m$^{-2}$. The extrapolation of the MAGIC spectrum into the GeV energy range matches the previously published \textit{Fermi}--LAT spectrum well, covering a combined energy range of four orders of magnitude with the same spectral index. We model the broad band energy spectrum with a spine layer model, which can satisfactorily describe our data., Comment: 8 pages, 5 figures, 2 tables; A&A Journal version, fixed typo in the author list
Published: 2012
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180. High zenith angle observations of PKS 2155-304 with the MAGIC-I telescope

Author: The MAGIC Collaboration, Aleksić, J., Antonelli, L. A., Antoranz, P., Asensio, M., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnoli, G., Tridon, D. Borla, Bretz, T., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., del Pozo, E. De Cea, De Lotto, B., Mendez, C. Delgado, Ortega, A. Diago, Doert, M., Prester, D. Dominis, Dorner, D., Doro, M., Eisenacher, D., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Giavitto, G., Godinović, N., Muñoz, A. González, Gozzini, S. R., Hadamek, A., Hadasch, D., Häfner, D., Herrero, A., Hose, J., Hrupec, D., Huber, B., Jankowski, F., Jogler, T., Kadenius, V., Klepser, S., Knoetig, M. L., Krähenbühl, T., Krause, J., Kushida, J., La Barbera, A., Lelas, D., Leonardo, E., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Makariev, M., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Moldón, J., Moralejo, A., Munar-Adrover, P., Niedzwiecki, A., Nieto, D., Nilsson, K., Nowak, N., Orito, R., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Partini, S., Persic, M., Pilia, M., Pochon, J., Prada, F., Moroni, P. G. Prada, Prandini, E., Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rügamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Spiro, S., Stamatescu, V., Stamerra, A., Steinke, B., Storz, J., Sun, S., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Tibolla, O., Torres, D. F., Toyama, T., Treves, A., Uellenbeck, M., Vogler, P., Wagner, R. M., Weitzel, Q., Zabalza, V., Zandanel, F., and Zanin, R.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: The high frequency peaked BL Lac PKS 2155-304 with a redshift of z=0.116 was discovered in 1997 in the very high energy (VHE, E >100GeV) gamma-ray range by the University of Durham Mark VI gamma-ray Cherenkov telescope in Australia with a flux corresponding to 20% of the Crab Nebula flux. It was later observed and detected with high significance by the Southern Cherenkov observatory H.E.S.S. Detection from the Northern hemisphere is difficult due to challenging observation conditions under large zenith angles. In July 2006, the H.E.S.S. collaboration reported an extraordinary outburst of VHE gamma-emission. During the outburst, the VHE gamma-ray emission was found to be variable on the time scales of minutes and with a mean flux of ~7 times the flux observed from the Crab Nebula. Follow-up observations with the MAGIC-I standalone Cherenkov telescope were triggered by this extraordinary outburst and PKS 2155-304 was observed between 28 July to 2 August 2006 for 15 hours at large zenith angles. Here we present our studies on the behavior of the source after its extraordinary flare and an enhanced analysis method for data taken at high zenith angles. We developed improved methods for event selection that led to a better background suppression. The averaged energy spectrum we derived has a spectral index of -3.5 +/- 0.2 above 400GeV, which is in good agreement with the spectral shape measured by H.E.S.S. during the major flare on MJD 53944. Furthermore, we present the spectral energy distribution modeling of PKS 2155-304. With our observations we increased the duty cycle of the source extending the light curve derived by H.E.S.S. after the outburst. Finally, we find night-by-night variability with a maximal amplitude of a factor three to four and an intranight variability in one of the nights (MJD 53945) with a similar amplitude., Comment: 10 pages, 9 figures; Accepted for publication in A&A
Published: 2012
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181. Search for radio pulsations in LS I +61 303

Author: Cañellas, A., Joshi, B. C., Paredes, J. M., Ishwara-Chandra, C. H., Moldón, J., Zabalza, V., Martí, J., and Ribó, M.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Context. LS I +61 303 is a member of the select group of gamma-ray binaries: galactic binary systems that contain a massive star and a compact object, show a changing milliarcsecond morphology and a similar broad spectral energy distribution (SED) that peaks at MeV-TeV energies and is modulated by the orbital motion. The nature of the compact object is unclear in LS I +61 303, LS 5039 and HESS J0632+057, whereas PSR B1259-63 harbours a 47.74 ms radio pulsar. Aims. A scenario in which a young pulsar wind interacts with the stellar wind has been proposed to explain the very high energy (VHE, E > 100 GeV) gamma-ray emission detected from LS I +61 303, although no pulses have been reported from this system at any wavelength. We aim to find evidence of the pulsar nature of the compact object. Methods. We performed phased array observations with the Giant Metrewave Radio Telescope (GMRT) at 1280 MHz centred at phase 0.54. Simultaneous data from the multi-bit phased array (PA) back-end with a sampling time of tsamp = 128 microsec and from the polarimeter (PMT) back-end with tsamp = 256 microsec where taken. Results. No pulses have been found in the data set, with a minimum detectable mean flux density of \sim 0.38 mJy at 8-sigma level for the pulsed emission from a putative pulsar with period P >2 ms and duty cycle D = 10% in the direction of LS I +61 303. Conclusions. The detection of posible radio pulsations will require deep and sensitive observations at frequencies \sim0.5-5 GHz and orbital phases 0.6-0.7. However, it may be unfeasible to detect pulses if the putative pulsar is not beamed at the Earth or if there is a strong absorption within the binary system., Comment: 8 pages. 5 figures. Accepted for publication in Astronomy and Astrophysics
Published: 2012
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182. On the origin of LS 5039 and PSR J1825-1446

Author: Moldón, J., Ribó, M., Paredes, J. M., Brisken, W., Dhawan, V., Kramer, M., Lyne, A. G., and Stappers, B. W.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
Abstract: Context. The gamma-ray binary LS 5039 and the isolated pulsar PSR J1825-1446 were proposed to have been formed in the supernova remnant (SNR) G016.8-01.1. Aims. We aim to obtain the Galactic trajectory of LS 5039 and PSR J1825-1446 to find their origin in the Galaxy, and in particular to check their association with SNR G016.8-01.1 to restrict their age. Methods. By means of radio and optical observations we obtained the proper motion and the space velocity of the sources. Results. The proper motion of PSR J1825-1446 corresponds to a transverse space velocity of 690 km/s at a distance of 5 kpc. Its Galactic velocity at different distances is not compatible with the expected Galactic rotation. The velocity and characteristic age of PSR J1825-1446 make it incompatible with SNR G016.8-01.1. There are no clear OB associations or SNRs crossing the past trajectory of PSR J1825-1446. We estimate the age of the pulsar to be 80-245 kyr, which is compatible with its characteristic age. The proper motion of LS 5039 is 7.09 and -8.82 mas/yr in right ascension and declination, respectively. The association of LS 5039 with SNR G016.8-01.1 is unlikely, although we cannot to discard it. The system would have had to be formed in the association Ser OB2 (at 2.0 kpc) if the age of the system is 1.0-1.2 Myr, or in the association Sct OB3 (distance 1.5-2 kpc) for an age of 0.1-0.2 Myr. If the system were not formed close to Ser OB2, the pseudo-synchronization of the orbit would be unlikely. Conclusions. PSR J1825-1446 is a high-velocity isolated pulsar ejected from the Galaxy. The distance to LS 5039, which needs to be constrained by future astrometric missions such as Gaia, is a key parameter for restricting its origin and age., Comment: 18 pages, 9 figures. Accepted for publication in Astronomy and Astrophysics
Published: 2012
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183. Detection of VHE \gamma-rays from HESS J0632+057 during the 2011 February X-ray outburst with the MAGIC Telescopes

Author: The MAGIC Collaboration, Aleksić, J., Alvarez, E. A., Antonelli, L. A., Antoranz, P., Asensio, M., Backes, M., de Almeida, U. Barres, Barrio, J. A., Bastieri, D., González, J. Becerra, Bednarek, W., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnoli, G., Tridon, D. Borla, Bosch-Ramon, V., Bretz, T., Cañellas, A., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., del Pozo, E. De Cea, De Lotto, B., Mendez, C. Delgado, Ortega, A. Diago, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Eisenacher, D., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Giavitto, G., Godinović, N., Muñoz, A. González, Gozzini, S. R., Hadasch, D., Häfner, D., Herrero, A., Hildebrand, D., Hose, J., Hrupec, D., Huber, B., Jankowski, F., Jogler, T., Kadenius, V., Kellermann, H., Klepser, S., Krähenbühl, T., Krause, J., La Barbera, A., Lelas, D., Leonardo, E., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Makariev, M., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Moldón, J., Moralejo, A., Munar-Adrover, P., Niedzwiecki, A., Nieto, D., Nilsson, K., Nowak, N., Orito, R., Paiano, S., Paneque, D., Paoletti, R., Pardo, S., Paredes, J. M., Partini, S., Perez-Torres, M. A., Persic, M., Pilia, M., Pochon, J., Prada, F., Moroni, P. G. Prada, Prandini, E., Gimenez, I. Puerto, Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rügamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Spiro, S., Stamatescu, V., Stamerra, A., Steinke, B., Storz, J., Strah, N., Sun, S., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Tibolla, O., Torres, D. F., Treves, A., Uellenbeck, M., Vogler, P., Wagner, R. M., Weitzel, Q., Zabalza, V., Zandanel, F., and Zanin, R.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The very high energy (VHE) \gamma-ray source HESS J0632+057 has recently been confirmed to be a \gamma-ray binary. The optical counterpart is the Be star MWC 148, and a compact object of unknown nature orbits it every ~321 d with a high eccentricity of ~0.8. We monitored HESS J0632+057 with the stereoscopic MAGIC telescopes from 2010 October to 2011 March and detected significant VHE \gamma-ray emission during 2011 February, when the system exhibited an X-ray outburst. We find no \gamma-ray signal in the other observation periods when the system did not show increased X-ray flux. Thus HESS J0632+057 exhibits \gamma-ray variability on timescales of the order of one to two months possibly linked to the X-ray outburst that takes place about 100 days after the periastron passage. Furthermore our measurements provide for the first time the \gamma-ray spectrum down to about 140 GeV and indicate no turnover of the spectrum at low energies. We compare the properties of HESS J0632+057 with the similar \gamma-ray binary LS I +61 303, and discuss on the possible origin of the multi-wavelength emission of the source, Comment: 6 pages and 3 figures, submitted, corresponding authors T. Jogler and P. Munar-Adrover
Published: 2012
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184. Discovery of VHE gamma-rays from the blazar 1ES 1215+303 with the MAGIC Telescopes and simultaneous multi-wavelength observations

Author: MAGIC Collaboration, Aleksić, J., Alvarez, E. A., Antonelli, L. A., Antoranz, P., Ansoldi, S., Asensio, M., Backes, M., de Almeida, U. Barres, Barrio, J. A., Bastieri, D., González, J. Becerra, Bednarek, W., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnoli, G., Tridon, D. Borla, Bretz, T., Cañellas, A., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., del Pozo, E. De Cea, De Lotto, B., Mendez, C. Delgado, Ortega, A. Diago, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Eisenacher, D., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Giavitto, G., Godinović, N., Muñoz, A. González, Gozzini, S. R., Hadasch, D., Häfner, D., Herrero, A., Hildebrand, D., Hose, J., Hrupec, D., Huber, B., Jankowski, F., Jogler, T., Kadenius, V., Kellermann, H., Klepser, S., Krähenbühl, T., Krause, J., La Barbera, A., Lelas, D., Leonardo, E., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Makariev, M., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Moldón, J., Moralejo, A., Munar-Adrover, P., Niedzwiecki, A., Nieto, D., Nilsson, K., Nowak, N., Orito, R., Paiano, S., Paneque, D., Paoletti, R., Pardo, S., Paredes, J. M., Partini, S., Perez-Torres, M. A., Persic, M., Pilia, M., Pochon, J., Prada, F., Moroni, P. G. Prada, Prandini, E., Gimenez, I. Puerto, Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rügamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Spiro, S., Stamatescu, V., Stamerra, A., Steinke, B., Storz, J., Strah, N., Sun, S., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Tibolla, O., Torres, D. F., Treves, A., Uellenbeck, M., Vogler, P., Wagner, R. M., Weitzel, Q., Zabalza, V., Zandanel, F., Zanin, R., Berdyugin, A., Buson, S., Järvelä, E., Larsson, S., Lähteenmäki, A., and Tammi, J.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Context. We present the discovery of very high energy (VHE, E > 100GeV) gamma-ray emission from the BL Lac object 1ES 1215+303 by the MAGIC telescopes and simultaneous multi-wavelength data in a broad energy range from radio to gamma-rays. Aims. We study the VHE gamma-ray emission from 1ES 1215+303 and its relation to the emissions in other wavelengths. Methods. Triggered by an optical outburst, MAGIC observed the source in January-February 2011 for 20.3 hrs. The target was monitored in the optical R-band by the KVA telescope that also performed optical polarization measurements. We triggered target of opportunity observations with the Swift satellite and obtained simultaneous and quasi-simultaneous data from the Fermi Large Area Telescope and from the Mets\"ahovi radio telescope. We also present the analysis of older MAGIC data taken in 2010. Results. The MAGIC observations of 1ES 1215+303 carried out in January-February 2011 resulted in the first detection of the source at VHE with a statistical significance of 9.4 sigma. Simultaneously, the source was observed in a high optical and X-ray state. In 2010 the source was observed in a lower state in optical, X-ray, and VHE, while the GeV gamma-ray flux and the radio flux were comparable in 2010 and 2011. The spectral energy distribution obtained with the 2011 data can be modeled with a simple one zone SSC model, but it requires extreme values for the Doppler factor or the electron energy distribution., Comment: 10 pages, 8 figures, accepted to A&A
Published: 2012
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185. Morphological and spectral properties of the W51 region measured with the MAGIC telescopes

Author: MAGIC Collaboration, Aleksić, J., Alvarez, E. A., Antonelli, L. A., Antoranz, P., Asensio, M., Backes, M., de Almeida, U. Barres, Barrio, J. A., Bastieri, D., González, J. Becerra, Bednarek, W., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnoli, G., Tridon, D. Borla, Bretz, T., Cañellas, A., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., del Pozo, E. De Cea, De Lotto, B., Mendez, C. Delgado, Ortega, A. Diago, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Eisenacher, D., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., López, R. J. García, Garczarczyk, M., Garrido, D., Giavitto, G., Godinović, N., Muñoz, A. González, Gozzini, S. R., Hadasch, D., Häfner, D., Herrero, A., Hildebrand, D., Hose, J., Hrupec, D., Huber, B., Jankowski, F., Jogler, T., Kadenius, V., Kellermann, H., Klepser, S., Krähenbühl, T., Krause, J., La Barbera, A., Lelas, D., Leonardo, E., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Makariev, M., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Moldón, J., Moralejo, A., Munar-Adrover, P., Niedzwiecki, A., Nieto, D., Nilsson, K., Nowak, N., Orito, R., Paiano, S., Paneque, D., Paoletti, R., Pardo, S., Paredes, J. M., Partini, S., Perez-Torres, M. A., Persic, M., Pilia, M., Pochon, J., Prada, F., Moroni, P. G. Prada, Prandini, E., Gimenez, I. Puerto, Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rügamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Spiro, S., Stamatescu, V., Stamerra, A., Steinke, B., Storz, J., Strah, N., Sun, S., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Tibolla, O., Torres, D. F., Treves, A., Uellenbeck, M., Vogler, P., Wagner, R. M., Weitzel, Q., Zabalza, V., Zandanel, F., and Zanin, R.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The W51 complex hosts the supernova remnant W51C which is known to interact with the molecular clouds in the star forming region W51B. In addition, a possible pulsar wind nebula CXO J192318.5+140305 was found likely associated with the supernova remnant. Gamma-ray emission from this region was discovered by Fermi/LAT (between 0.2 and 50 GeV) and H.E.S.S. (>1 TeV). The spatial distribution of the events could not be used to pinpoint the location of the emission among the pulsar wind nebula, the supernova remnant shell and/or the molecular cloud. However, the modeling of the spectral energy distribution presented by the Fermi/LAT collaboration suggests a hadronic emission mechanism. We performed observations of the W51 complex with the MAGIC telescopes for more than 50 hours. The good angular resolution in the medium (few hundred GeV) to high (above 1 TeV) energies allow us to perform morphological studies. We detect an extended emission of very-high-energy gamma rays, with a significance of 11 standard deviations. We extend the spectrum from the highest Fermi/LAT energies to \sim 5 TeV and find that it follows a single power law with an index of 2.58 \pm 0.07stat \pm 0.22syst . The main part of the emission coincides with the shocked cloud region, while we find a feature extending towards the pulsar wind nebula. The possible contribution of the pulsar wind nebula, assuming a point-like source, shows no dependence on energy and it is about 20% of the overall emission. The broad band spectral energy distribution can be explained with a hadronic model that implies proton acceleration above 100 TeV. This result, together with the morphology of the source, tentatively suggests that we observe ongoing acceleration of ions in the interaction zone between supernova remnant and cloud. These results shed light on the long-standing problem of the origin of galactic cosmic rays., Comment: 11 pages, 7 figures, accepted by A&A, corresponding authors: J. Krause, I Reichardt, E. Carmona
Published: 2012
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186. Discovery of VHE gamma-ray emission from the BL Lac object B3 2247+381 with the MAGIC telescopes

Author: The MAGIC Collaboration, Aleksić, J., Alvarez, E. A., Antonelli, L. A., Antoranz, P., Asensio, M., Backes, M., Barrio, J. A., Bastieri, D., González, J. Becerra, Bednarek, W., Berdyugin, A., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnoli, G., Tridon, D. Borla, Braun, I., Bretz, T., Cañellas, A., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Dazzi, F., De Angelis, A., De Caneva, G., del Pozo, E. De Cea, De Lotto, B., Mendez, C. Delgado, Ortega, A. Diago, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., López, R. J. García, Garczarczyk, M., Garrido, D., Giavitto, G., Godinović, N., Hadasch, D., Häfner, D., Herrero, A., Hildebrand, D., Höhne-Mönch, D., Hose, J., Hrupec, D., Huber, B., Jogler, T., Kellermann, H., Klepser, S., Krähenbühl, T., Krause, J., La Barbera, A., Lelas, D., Leonardo, E., Lindfors, E., Lombardi, S., López, M., López-Oramas, A., Lorenz, E., Makariev, M., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Miyamoto, H., Moldón, J., Moralejo, A., Munar-Adrover, P., Nieto, D., Nilsson, K., Orito, R., Oya, I., Paneque, D., Paoletti, R., Pardo, S., Paredes, J. M., Partini, S., Pasanen, M., Pauss, F., Perez-Torres, M. A., Persic, M., Peruzzo, L., Pilia, M., Pochon, J., Prada, F., Moroni, P. G. Prada, Prandini, E., Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rügamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shayduk, M., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Spiro, S., Stamatescu, V., Stamerra, A., Steinke, B., Storz, J., Strah, N., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Tibolla, O., Torres, D. F., Treves, A., Uellenbeck, M., Vankov, H., Vogler, P., Wagner, R. M., Weitzel, Q., Zabalza, V., Zandanel, F., Zanin, R., Kadenius, V., Weidinger, M., and Buson, S.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: We study the non-thermal jet emission of the BL Lac object B3 2247+381 during a high optical state. The MAGIC telescopes observed the source during 13 nights between September 30th and October 30th 2010, collecting a total of 14.2 hours of good quality very high energy (VHE) $\gamma$-ray data. Simultaneous multiwavelength data was obtained with X-ray observations by the Swift satellite and optical R-band observations at the KVA-telescope. We also use high energy $\gamma$-ray (HE, 0.1 GeV-100 GeV) data from the Fermi satellite. The BL Lac object B3 2247+381 (z=0.119) was detected, for the first time, at VHE $\gamma$-rays at a statistical significance of 5.6 $\sigma$. A soft VHE spectrum with a photon index of -3.2 $\pm$ 0.6 was determined. No significant short term flux variations were found. We model the spectral energy distribution using a one-zone SSC-model, which can successfully describe our data., Comment: 7 pages, 6 figures, 1 table, accepted for publication in Astronomy and Astrophysics
Published: 2012
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187. On the binary nature of the gamma-ray sources AGL J2241+4454 (=MWC 656) and HESS J0632+057 (=MWC 148)

Author: Casares, J., Ribo, M., Ribas, I., Paredes, J. M., Vilardell, F., and Negueruela, I.
Subjects: Astrophysics - Solar and Stellar Astrophysics
Abstract: We present optical spectroscopy of MWC 656 and MWC 148, the proposed optical counterparts of the gamma-ray sources AGL J2241+4454 and HESS J0632+0 57, respectively. The main parameters of the Halpha emission line (EW, FWHM and centroid velocity) in these stars are modulated on the proposed orbital periods of 60.37 and 321 days, respectively. These modulations are likely produced by the resonant interaction of the Be discs with compact stars in eccentric orbits. We also present radial velocity curves of the optical stars folded on the above periods and obtain the first orbital elements of the two gamma-ray sources thus confirming their binary nature. Our orbital solution support eccentricities e~0.4 and 0.83+-0.08 for MWC 656 and MWC 148, respectively. Further, our orbital elements imply that the X-ray outbursts in HESS J0632+057/MWC 148 are delayed ~0.3 orbital phases after periastron passage, similarly to the case of LS I +61 303. In addition, the optical photometric light curve maxima in AGL J2241+4454/MWC 656 occur ~0.25 phases passed periastron, similar to what is seen in LS I +61 303. We also find that the orbital eccentricity is correlated with orbital period for the known gamma-ray binaries. This is explained by the fact that small stellar separations are required for the efficient triggering of VHE radiation. Another correlation between the EW of Halpha and orbital period is also observed, similarly to the case of Be/X-ray binaries. These correlations are useful to provide estimates of the key orbital parameters Porb and e from the Halpha line in future Be gamma-ray binary candidates., Comment: Figure 4 replaced by new version which corrects phases in right-hand panel
Published: 2012
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188. Detection of very-high energy \gamma-ray emission from NGC 1275 by the MAGIC telescopes

Author: MAGIC Collaboration, Aleksić, J., Alvarez, E. A., Antonelli, L. A., Antoranz, P., Asensio, M., Backes, M., de Almeida, U. Barres, Barrio, J. A., Bastieri, D., González, J. Becerra, Bednarek, W., Berdyugin, A., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnoli, G., Tridon, D. Borla, Braun, I., Bretz, T., Cañellas, A., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Dazzi, F., De Angelis, A., De Caneva, G., del Pozo, E. De Cea, De Lotto, B., Mendez, C. Delgado, Ortega, A. Diago, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Eisenacher, D., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., López, R. J. García, Garczarczyk, M., Garrido, D., Giavitto, G., Godinović, N., Gozzini, S. R., Hadasch, D., Häfner, D., Herrero, A., Hildebrand, D., Höhne-Mönch, D., Hose, J., Hrupec, D., Jogler, T., Kellermann, H., Klepser, S., Krähenbühl, T., Krause, J., Kushida, J., La Barbera, A., Lelas, D., Leonardo, E., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Makariev, M., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Moldón, J., Moralejo, A., Munar-Adrover, P., Niedzwiecki, A., Nieto, D., Nilsson, K., Nowak, N., Orito, R., Paiano, S., Paneque, D., Paoletti, R., Pardo, S., Paredes, J. M., Partini, S., Perez-Torres, M. A., Persic, M., Peruzzo, L., Pilia, M., Pochon, J., Prada, F., Moroni, P. G. Prada, Prandini, E., Gimenez, I. Puerto, Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rügamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shayduk, M., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Spiro, S., Stamatescu, V., Stamerra, A., Steinke, B., Storz, J., Strah, N., Sun, S., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Tibolla, O., Torres, D. F., Treves, A., Uellenbeck, M., Vankov, H., Vogler, P., Wagner, R. M., Weitzel, Q., Zabalza, V., Zandanel, F., Zanin, R., Pfrommer, C., and Pinzke, A.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report on the detection of very-high energy (VHE, E>100 GeV) gamma-ray emission from NGC 1275, the central radio galaxy of the Perseus cluster of galaxies. The source has been detected by the MAGIC telescopes with a statistical significance of 6.6 sigma above 100 GeV in 46 hr of stereo observations carried out between August 2010 and February 2011. The measured differential energy spectrum between 70 GeV and 500 GeV can be described by a power law with a steep spectral index of \Gamma=-4.1+/-0.7stat+/-0.3syst, and the average flux above 100 GeV is F_{gamma}=(1.3+/-0.2stat+/-0.3syst) x 10^-11 cm^-2 s^-1. These results, combined with the power-law spectrum measured in the first two years of observations by the Fermi-LAT above 100 MeV, with a spectral index of Gamma ~ -2.1, strongly suggest the presence of a break or cut-off around tens of GeV in the NGC 1275 spectrum. The light curve of the source above 100 GeV does not show hints of variability on a month time scale. Finally, we report on the nondetection in the present data of the radio galaxy IC 310, previously discovered by the Fermi-LAT and MAGIC. The derived flux upper limit F^{U.L.}_{gamma} (>300 GeV)=1.2 x 10^-12 cm^-2 s^-1 is a factor ~ 3 lower than the mean flux measured by MAGIC between October 2009 and February 2010, thus confirming the year time-scale variability of the source at VHE., Comment: Corresponding authors are S. Lombardi, P. Colin, D. Hildebrand, and F. Zandanel. Published in A&A; 4 pages, 4 figures
Published: 2011
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189. Detection of the gamma-ray binary LS I +61 303 in a low flux state at Very High Energy gamma-rays with the MAGIC Telescopes in 2009

Author: MAGIC Collaboration, Aleksić, J., Alvarez, E. A., Antonelli, L. A., Antoranz, P., Asensio, M., Backes, M., Barrio, J. A., Bastieri, D., González, J. Becerra, Bednarek, W., Berdyugin, A., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnoli, G., Tridon, D. Borla, Bosch-Ramon, V., Braun, I., Bretz, T., Cañellas, A., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Dazzi, F., De Angelis, A., De Caneva, G., del Pozo, E. De Cea, De Lotto, B., Mendez, C. Delgado, Ortega, A. Diago, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., López, R. J. García, Garczarczyk, M., Garrido, D., Giavitto, G., Godinović, N., Hadasch, D., Häfner, D., Herrero, A., Hildebrand, D., Höhne-Mönch, D., Hose, J., Hrupec, D., Huber, B., Jogler, T., Kellermann, H., Klepser, S., Krähenbühl, T., Krause, J., La Barbera, A., Lelas, D., Leonardo, E., Lindfors, E., Lombardi, S., López, M., López-Oramas, A., Lorenz, E., Makariev, M., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Miyamoto, H., Moldón, J., Moralejo, A., Munar-Adrover, P., Nieto, D., Nilsson, K., Orito, R., Oya, I., Paneque, D., Paoletti, R., Pardo, S., Paredes, J. M., Partini, S., Pasanen, M., Pauss, F., Perez-Torres, M. A., Persic, M., Peruzzo, L., Pilia, M., Pochon, J., Prada, F., Moroni, P. G. Prada, Prandini, E., Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rügamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shayduk, M., Shore, S. N., Sillanpää, A., Sitarek, J., Sobczynska, D., Spanier, F., Spiro, S., Stamatescu, V., Stamerra, A., Steinke, B., Storz, J., Strah, N., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Tibolla, O., Torres, D. F., Treves, A., Uellenbeck, M., Vankov, H., Vogler, P., Wagner, R. M., Weitzel, Q., Zabalza, V., Zandanel, F., and Zanin, R.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present very high energy (VHE, E > 100 GeV) {\gamma}-ray observations of the {\gamma}-ray binary system LS I+61 303 obtained with the MAGIC stereo system between 2009 October and 2010 January. We detect a 6.3{\sigma} {\gamma}-ray signal above 400 GeV in the combined data set. The integral flux above an energy of 300 GeV is F(E>300 GeV)=(1.4 +- 0.3stat +- 0.4syst) * 10^{-12} cm^{-2} s^{-1}, which corresponds to about 1.3% of the Crab Nebula flux in the same energy range. The orbit-averaged flux of LS I +61 303 in the orbital phase interval 0.6--0.7, where a maximum of the TeV flux is expected, is lower by almost an order of magnitude compared to our previous measurements between 2005 September and 2008 January. This provides evidence for a new low emission state in LS I +61 303. We find that the change to the low flux state cannot be solely explained by an increase of photon-photon absorption around the compact star., Comment: Corresponding authors: T. Jogler and O. Blanch; accepted for publication in ApJ, 6 pages and 3 figures
Published: 2011
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190. Constraining Cosmic Rays and Magnetic Fields in the Perseus Galaxy Cluster with TeV observations by the MAGIC telescopes

Author: MAGIC Collaboration, Aleksić, J., Alvarez, E. A., Antonelli, L. A., Antoranz, P., Asensio, M., Backes, M., de Almeida, U. Barres, Barrio, J. A., Bastieri, D., González, J. Becerra, Bednarek, W., Berdyugin, A., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnoli, G., Tridon, D. Borla, Braun, I., Bretz, T., Cañellas, A., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Dazzi, F., De Angelis, A., De Caneva, G., del Pozo, E. De Cea, De Lotto, B., Mendez, C. Delgado, Ortega, A. Diago, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Eisenacher, D., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., López, R. J. García, Garczarczyk, M., Garrido, D., Giavitto, G., Godinović, N., Gozzini, S. R., Hadasch, D., Häfner, D., Herrero, A., Hildebrand, D., Höhne-Mönch, D., Hose, J., Hrupec, D., Jogler, T., Kellermann, H., Klepser, S., Krähenbühl, T., Krause, J., Kushida, J., La Barbera, A., Lelas, D., Leonardo, E., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Makariev, M., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Moldón, J., Moralejo, A., Munar-Adrover, P., Niedzwiecki, A., Nieto, D., Nilsson, K., Nowak, N., Orito, R., Paiano, S., Paneque, D., Paoletti, R., Pardo, S., Paredes, J. M., Partini, S., Perez-Torres, M. A., Persic, M., Peruzzo, L., Pilia, M., Pochon, J., Prada, F., Moroni, P. G. Prada, Prandini, E., Gimenez, I. Puerto, Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rügamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shayduk, M., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Spiro, S., Stamatescu, V., Stamerra, A., Steinke, B., Storz, J., Strah, N., Sun, S., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Tibolla, O., Torres, D. F., Treves, A., Uellenbeck, M., Vankov, H., Vogler, P., Wagner, R. M., Weitzel, Q., Zabalza, V., Zandanel, F., Zanin, R., Pfrommer, C., and Pinzke, A.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Extragalactic Astrophysics
Abstract: Galaxy clusters are being assembled today in the most energetic phase of hierarchical structure formation which manifests itself in powerful shocks that contribute to a substantial energy density of cosmic rays (CRs). Hence, clusters are expected to be luminous gamma-ray emitters since they also act as energy reservoirs for additional CR sources, such as active galactic nuclei and supernova-driven galactic winds. To detect the gamma-ray emission from CR interactions with the ambient cluster gas, we conducted the deepest to date observational campaign targeting a galaxy cluster at very high-energy gamma-rays and observed the Perseus cluster with the MAGIC Cherenkov telescopes for a total of ~85 hr of effective observing time. This campaign resulted in the detection of the central radio galaxy NGC 1275 at energies E > 100 GeV with a very steep energy spectrum. Here, we restrict our analysis to energies E > 630 GeV and detect no significant gamma-ray excess. This constrains the average CR-to-thermal pressure ratio to be <= 1-2%, depending on assumptions and the model for CR emission. Comparing these gamma-ray upper limits to predictions from cosmological cluster simulations that include CRs constrains the maximum CR acceleration efficiency at structure formation shocks to be < 50%. Alternatively, this may argue for non-negligible CR transport processes such as CR streaming and diffusion into the outer cluster regions. Finally, we derive lower limits on the magnetic field distribution assuming that the Perseus radio mini-halo is generated by secondary electrons/positrons that are created in hadronic CR interactions: assuming a spectrum of E^-2.2 around TeV energies as implied by cluster simulations, we limit the central magnetic field to be > 4-9 microG, depending on the rate of decline of the magnetic field strength toward larger radii., Comment: Corresponding authors are F. Zandanel, C. Pfrommer, P. Colin, A. Pinzke and S. Lombardi. Accepted for publication in A&A on 06/03/2012
Published: 2011
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191. The 2010 very high energy gamma-ray flare & 10 years of multi-wavelength observations of M 87

Author: Collaboration, The H. E. S. S., Abramowski, A., Acero, F., Aharonian, F., Akhperjanian, A. G., Anton, G., Balzer, A., Barnacka, A., de Almeida, U. Barres, Becherini, Y., Becker, J., Behera, B., Bernlöhr, K., Birsin, E., Biteau, J., Bochow, A., Boisson, C., Bolmont, J., Bordas, P., Brucker, J., Brun, F., Brun, P., Bulik, T., Büsching, I., Carrigan, S., Casanova, S., Cerruti, M., Chadwick, P. M., Charbonnier, A., Chaves, R. C. G., Cheesebrough, A., Clapson, A. C., Coignet, G., Cologna, G., Conrad, J., Dalton, M., Daniel, M. K., Davids, I. D., Degrange, B., Deil, C., Dickinson, H. J., Djannati-Ataï, A., Domainko, W., Drury, L. O'C., Dubus, G., Dutson, K., Dyks, J., Dyrda, M., Egberts, K., Eger, P., Espigat, P., Fallon, L., Farnier, C., Fegan, S., Feinstein, F., Fernandes, M. V., Fiasson, A., Fontaine, G., Förster, A., Füßling, M., Gallant, Y. A., Gast, H., Gérard, L., Gerbig, D., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Göring, D., Häffner, S., Hague, J. D., Hampf, D., Hauser, M., Heinz, S., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Hofverberg, P., Holler, M., Horns, D., Jacholkowska, A., de Jager, O. C., Jahn, C., Jamrozy, M., Jung, I., Kastendieck, M. A., Katarzyński, K., Katz, U., Kaufmann, S., Keogh, D., Khangulyan, D., Khélifi, B., Klochkov, D., Kluźniak, W., Kneiske, T., Komin, Nu., Kosack, K., Kossakowski, R., Laffon, H., Lamanna, G., Lennarz, D., Lohse, T., Lopatin, A., Lu, C. -C., Marandon, V., Marcowith, A., Masbou, J., Maurin, D., Maxted, N., Mayer, M., McComb, T. J. L., Medina, M. C., Méhault, J., Moderski, R., Moulin, E., Naumann, C. L., Naumann-Godo, M., de Naurois, M., Nedbal, D., Nekrassov, D., Nguyen, N., Nicholas, B., Niemiec, J., Nolan, S. J., Ohm, S., Wilhelmi, E. de Oña, Opitz, B., Ostrowski, M., Oya, I., Panter, M., Arribas, M. Paz, Pedaletti, G., Pelletier, G., Petrucci, P. -O., Pita, S., Pühlhofer, G., Punch, M., Quirrenbach, A., Raue, M., Rayner, S. M., Reimer, A., Reimer, O., Renaud, M., Reyes, R. de los, Rieger, F., Ripken, J., Rob, L., Rosier-Lees, S., Rowell, G., Rudak, B., Rulten, C. B., Ruppel, J., Sahakian, V., Sanchez, D. A., Santangelo, A., Schlickeiser, R., Schöck, F. M., Schulz, A., Schwanke, U., Schwarzburg, S., Schwemmer, S., Sheidaei, F., Skilton, J. L., Sol, H., Spengler, G., Stawarz, Ł., Steenkamp, R., Stegmann, C., Stinzing, F., Stycz, K., Sushch, I., Szostek, A., Tavernet, J. -P., Terrier, R., Tluczykont, M., Valerius, K., van Eldik, C., Vasileiadis, G., Venter, C., Vialle, J. P., Viana, A., Vincent, P., Völk, H. J., Volpe, F., Vorobiov, S., Vorster, M., Wagner, S. J., Ward, M., White, R., Wierzcholska, A., Zacharias, M., Zajczyk, A., Zdziarski, A. A., Zech, A., Zechlin, H. -S., Collaboration, The MAGIC, Aleksić, J., Antonelli, L. A., Antoranz, P., Backes, M., Barrio, J. A., Bastieri, D., González, J. Becerra, Bednarek, W., Berdyugin, A., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnoli, G., Tridon, D. Borla, Braun, I., Bretz, T., Cañellas, A., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Dazzi, F., De Angelis, A., del Pozo, E. De Cea, De Lotto, B., Mendez, C. Delgado, Ortega, A. Diago, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., López, R. J. García, Garczarczyk, M., Garrido, D., Giavitto, G., Godinović, N., Hadasch, D., Häfner, D., Herrero, A., Hildebrand, D., Höhne-Mönch, D., Hose, J., Hrupec, D., Huber, B., Jogler, T., Klepser, S., Krähenbühl, T., Krause, J., La Barbera, A., Lelas, D., Leonardo, E., Lindfors, E., Lombardi, S., López, M., Lorenz, E., Makariev, M., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Miyamoto, H., Moldón, J., Moralejo, A., Munar, P., Nieto, D., Nilsson, K., Orito, R., Paneque, D., Paoletti, R., Pardo, S., Paredes, J. M., Partini, S., Pasanen, M., Pauss, F., Perez-Torres, M. A., Persic, M., Peruzzo, L., Pilia, M., Pochon, J., Prada, F., Moroni, P. G. Prada, Prandini, E., Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rügamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shayduk, M., Shore, S. N., Sillanpää, A., Sitarek, J., Sobczynska, D., Spanier, F., Spiro, S., Stamerra, A., Steinke, B., Storz, J., Strah, N., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thom, M., Tibolla, O., Torres, D. F., Treves, A., Vankov, H., Vogler, P., Wagner, R. M., Weitzel, Q., Zabalza, V., Zandanel, F., Zanin, R., Collaboration, The VERITAS, Arlen, T., Aune, T., Beilicke, M., Benbow, W., Bouvier, A., Bradbury, S. M., Buckley, J. H., Bugaev, V., Byrum, K., Cannon, A., Cesarini, A., Ciupik, L., Connolly, M. P., Cui, W., Dickherber, R., Duke, C., Errando, M., Falcone, A., Finley, J. P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Godambe, S., Griffin, S., Grube, J., Gyuk, G., Hanna, D., Holder, J., Huan, H., Hui, C. M., Kaaret, P., Karlsson, N., Kertzman, M., Khassen, Y., Kieda, D., Krawczynski, H., Krennrich, F., Lang, M. J., LeBohec, S., Maier, G., McArthur, S., McCann, A., Moriarty, P., Mukherjee, R., Nuñez, P. D., Ong, R. A., Orr, M., Otte, A. N., Park, N., Perkins, J. S., Pichel, A., Pohl, M., Prokoph, H., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Rose, H. J., Schroedter, M., Sembroski, G. H., Şentürk, G. D., Telezhinsky, I., Tešić, G., Theiling, M., Thibadeau, S., Varlotta, A., Vassiliev, V. V., Vivier, M., Wakely, S. P., Weekes, T. C., Williams, D. A., Zitzer, B., Cara, M., Casadio, C., Cheung, C. C., McConville, W., Davies, F., Doi, A., Giovannini, G., Giroletti, M., Hada, K., Hardee, P., Harris, D. E., Junor, W., Kino, M., Lee, N. P., Ly, C., Madrid, J., Massaro, F., Mundell, C. G., Nagai, H., Perlman, E. S., Steele, I. A., Walker, R. C., and Wood, D. L.
Subjects: Astrophysics - Cosmology and Extragalactic Astrophysics
Abstract: Abridged: The giant radio galaxy M 87 with its proximity, famous jet, and very massive black hole provides a unique opportunity to investigate the origin of very high energy (VHE; E>100 GeV) gamma-ray emission generated in relativistic outflows and the surroundings of super-massive black holes. M 87 has been established as a VHE gamma-ray emitter since 2006. The VHE gamma-ray emission displays strong variability on timescales as short as a day. In this paper, results from a joint VHE monitoring campaign on M 87 by the MAGIC and VERITAS instruments in 2010 are reported. During the campaign, a flare at VHE was detected triggering further observations at VHE (H.E.S.S.), X-rays (Chandra), and radio (43 GHz VLBA). The excellent sampling of the VHE gamma-ray light curve enables one to derive a precise temporal characterization of the flare: the single, isolated flare is well described by a two-sided exponential function with significantly different flux rise and decay times. While the overall variability pattern of the 2010 flare appears somewhat different from that of previous VHE flares in 2005 and 2008, they share very similar timescales (~day), peak fluxes (Phi(>0.35 TeV) ~= (1-3) x 10^-11 ph cm^-2 s^-1), and VHE spectra. 43 GHz VLBA radio observations of the inner jet regions indicate no enhanced flux in 2010 in contrast to observations in 2008, where an increase of the radio flux of the innermost core regions coincided with a VHE flare. On the other hand, Chandra X-ray observations taken ~3 days after the peak of the VHE gamma-ray emission reveal an enhanced flux from the core. The long-term (2001-2010) multi-wavelength light curve of M 87, spanning from radio to VHE and including data from HST, LT, VLA and EVN, is used to further investigate the origin of the VHE gamma-ray emission. No unique, common MWL signature of the three VHE flares has been identified., Comment: 19 pages, 5 figures; Corresponding authors: M. Raue, L. Stawarz, D. Mazin, P. Colin, C. M. Hui, M. Beilicke; Fig. 1 lightcurve data available online: http://www.desy.de/~mraue/m87/
Published: 2011
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192. MAGIC contributions to the 32nd International Cosmic Ray Conference

Author: MAGIC Collaboration, Aleksić, J., Alvarez, E. A., Antonelli, L. A., Antoranz, P., Asensio, M., Backes, M., de Almeida, U. Barres, Barrio, J. A., Bastieri, D., González, J. Becerra, Bednarek, W., Berdyugin, A., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnoli, G., Tridon, D. Borla, Braun, I., Bretz, T., Cañellas, A., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Dazzi, F., De Angelis, A., De Caneva, G., del Pozo, E. De Cea, De Lotto, B., Mendez, C. Delgado, Ortega, A. Diago, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Eisenacher, D., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., López, R. J. García, Garczarczyk, M., Garrido, D., Giavitto, G., Godinović, N., Gozzini, S. R., Hadasch, D., Häfner, D., Herrero, A., Hildebrand, D., Höhne-Mönch, D., Hose, J., Hrupec, D., Jogler, T., Kellermann, H., Klepser, S., Krähenbühl, T., Krause, J., Kushida, J., La Barbera, A., Lelas, D., Leonardo, E., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López, R., López-Oramas, A., Lorenz, E., Makariev, M., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Moldón, J., Moralejo, A., Munar-Adrover, P., Niedzwiecki, A., Nieto, D., Nilsson, K., Nowak, N., Orito, R., Paiano, S., Paneque, D., Paoletti, R., Pardo, S., Paredes, J. M., Partini, S., Perez-Torres, M. A., Persic, M., Peruzzo, L., Pilia, M., Pochon, J., Prada, F., Moroni, P. G. Prada, Prandini, E., Gimenez, I. Puerto, Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rügamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shayduk, M., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Spiro, S., Stamatescu, V., Stamerra, A., Steinke, B., Storz, J., Strah, N., Sun, S., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Tibolla, O., Torres, D. F., Treves, A., Uellenbeck, M., Vankov, H., Vogler, P., Wagner, R. M., Weitzel, Q., Zabalza, V., Zandanel, F., and Zanin, R.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Compilation of the papers contributed by the MAGIC collaboration to the 32nd International Cosmic Ray Conference (ICRC 2011), which took place between August 11 and 18, 2011 in Beijing, China. The papers are sorted in 6 categories: Overview and Highlight papers; Instrument, software and techniques; Galactic sources; Extragalactic sources; Multi-wavelength and joint campaigns; Fundamental physics, dark matter and cosmic rays., Comment: Index of the MAGIC conference proceedings at the ICRC 2011 v2: added one missing paper; corrected author list; added affiliations; added ICRC acronym in the abstract
Published: 2011

193. MAGIC detection of the putative gamma-ray binary HESS J0632+057

Author: Jogler, T., Munar-Adrover, P., Ribó, M., and Paredes, J. M.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The variable gamma-ray source HESS J0632+057 is an excellent candidate for a gamma-ray binary. The putative binary system was discovered as a point-like VHE gamma-ray source by HESS. Later measurements by VERITAS yielding no detection, provided evidence for variable emission in the gamma-ray domain. A variable X-ray source as well as a Be star (MWC 148) are found at the location of the gamma-ray source. Recently a periodic X-ray outburst occurring about every 320 days was reported by Swift (ATel 3152). The putative binary system was observed by the MAGIC stereo system in 2010 and 2011. Our measurements demonstrate significant activity in the gamma-ray (E > 200 GeV) band in February 2011. Our detection of the system occurred during an X-ray outburst reported by Swift. Here we present the obtained light curve and spectrum during this outburst and put them into context with the X-ray measurements., Comment: 4 pages, In Proceedings of the 32nd International Cosmic Ray Conference (Beijing)
Published: 2011
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194. Phase-resolved energy spectra of the Crab Pulsar in the range of 50-400 GeV measured with the MAGIC Telescopes

Author: MAGIC Collaboration, Aleksić, J., Alvarez, E. A., Antonelli, L. A., Antoranz, P., Asensio, M., Backes, M., Barrio, J. A., Bastieri, D., González, J. Becerra, Bednarek, W., Berdyugin, A., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnoli, G., Tridon, D. Borla, Braun, I., Bretz, T., Cañellas, A., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Dazzi, F., De Angelis, A., De Caneva, G., del Pozo, E. De Cea, De Lotto, B., Mendez, C. Delgado, Ortega, A. Diago, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Eisenacher, D., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., López, R. J. García, Garczarczyk, M., Garrido, D., Giavitto, G., Godinović, N., Hadasch, D., Häfner, D., Herrero, A., Hildebrand, D., Höhne-Mönch, D., Hose, J., Hrupec, D., Jogler, T., Kellermann, H., Klepser, S., Krähenbühl, T., Krause, J., Kushida, J., La Barbera, A., Lelas, D., Leonardo, E., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López-Oramas, A., Lorenz, E., Makariev, M., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Moldón, J., Moralejo, A., Munar-Adrover, P., Niedzwiecki, A., Nieto, D., Nilsson, K., Nowak, N., Orito, R., Paneque, D., Paoletti, R., Pardo, S., Paredes, J. M., Partini, S., Perez-Torres, M. A., Persic, M., Peruzzo, L., Pilia, M., Pochon, J., Prada, F., Moroni, P. G. Prada, Prandini, E., Gimenez, I. Puerto, Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rügamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shayduk, M., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Spiro, S., Stamatescu, V., Stamerra, A., Steinke, B., Storz, J., Strah, N., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Tibolla, O., Torres, D. F., Treves, A., Uellenbeck, M., Vankov, H., Vogler, P., Wagner, R. M., Weitzel, Q., Zabalza, V., Zandanel, F., Zanin, R., and Hirotani, K.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We use 73 h of stereoscopic data taken with the MAGIC telescopes to investigate the very high-energy (VHE) gamma-ray emission of the Crab pulsar. Our data show a highly significant pulsed signal in the energy range from 50 to 400 GeV in both the main pulse (P1) and the interpulse (P2) phase regions. We provide the widest spectra to date of the VHE components of both peaks, and these spectra extend to the energy range of satellite-borne observatories. The good resolution and background rejection of the stereoscopic MAGIC system allows us to cross-check the correctness of each spectral point of the pulsar by comparison with the corresponding (strong and well-known) Crab nebula flux. The spectra of both P1 and P2 are compatible with power laws with photon indices of 4.0 \pm 0.8 (P1) and 3.42 \pm 0.26 (P2), respectively, and the ratio P1/P2 between the photon counts of the two pulses is 0.54 \pm 0.12. The VHE emission can be understood as an additional component produced by the inverse Compton scattering of secondary and tertiary e\pm pairs on IR-UV photons., Comment: 6 pages, 4 figures. Accepted for publication in A&A on 16 February 2012
Published: 2011
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195. Observations of the Crab pulsar between 25 GeV and 100 GeV with the MAGIC I telescope

Author: MAGIC Collaboration, Aleksić, J., Alvarez, E. A., Antonelli, L. A., Antoranz, P., Asensio, M., Backes, M., Barrio, J. A., Bastieri, D., González, J. Becerra, Bednarek, W., Berdyugin, A., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnoli, G., Tridon, D. Borla, Braun, I., Bretz, T., Cañellas, A., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Dazzi, F., De Angelis, A., De Caneva, G., del Pozo, E. De Cea, De Lotto, B., Mendez, C. Delgado, Ortega, A. Diago, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Eisenacher, D., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., López, R. J. García, Garczarczyk, M., Garrido, D., Giavitto, G., Godinović, N., Hadasch, D., Häfner, D., Herrero, A., Hildebrand, D., Höhne-Mönch, D., Hose, J., Hrupec, D., Jogler, T., Kellermann, H., Klepser, S., Krähenbühl, T., Krause, J., Kushida, J., La Barbera, A., Lelas, D., Leonardo, E., Lindfors, E., Lombardi, S., López, M., López-Oramas, A., Lorenz, E., Makariev, M., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Moldón, J., Moralejo, A., Munar-Adrover, P., Nieto, D., Nilsson, K., Orito, R., Otte, N., Oya, I., Paneque, D., Paoletti, R., Pardo, S., Paredes, J. M., Partini, S., Perez-Torres, M. A., Persic, M., Peruzzo, L., Pilia, M., Pochon, J., Prada, F., Moroni, P. G. Prada, Prandini, E., Gimenez, I. Puerto, Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rissi, M., Rügamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shayduk, M., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Spiro, S., Stamatescu, V., Stamerra, A., Steinke, B., Storz, J., Strah, N., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Tibolla, O., Torres, D. F., Treves, A., Uellenbeck, M., Vankov, H., Vogler, P., Wagner, R. M., Weitzel, Q., Zabalza, V., Zandanel, F., Zanin, R., and Hirotani, K.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report on the observation of $\gamma$-rays above 25\,GeV from the Crab pulsar (PSR B0532+21) using the MAGIC I telescope. Two data sets from observations during the winter period 2007/2008 and 2008/2009 are used. In order to discuss the spectral shape from 100\,MeV to 100\,GeV, one year of public {\it Fermi} Large Area Telescope ({\it Fermi}-LAT) data are also analyzed to complement the MAGIC data. The extrapolation of the exponential cutoff spectrum determined with the Fermi-LAT data is inconsistent with MAGIC measurements, which requires a modification of the standard pulsar emission models. In the energy region between 25 and 100\,GeV, the emission in the P1 phase (from -0.06 to 0.04, location of the main pulse) and the P2 phase (from 0.32 to 0.43, location of the interpulse) can be described by power laws with spectral indices of $-3.1 \pm 1.0_{stat} \pm 0.3_{syst}$ and $-3.5 \pm 0.5_{stat} \pm 0.3_{syst}$, respectively. Assuming an asymmetric Lorentzian for the pulse shape, the peak positions of the main pulse and the interpulse are estimated to be at phases $-0.009 \pm 0.007$ and $0.393 \pm 0.009$, while the full widths at half maximum are $0.025 \pm 0.008$ and $0.053 \pm 0.015$, respectively., Comment: 14 pages, 15 figures, published in Astrophysical Journal
Published: 2011
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196. Performance of the MAGIC stereo system obtained with Crab Nebula data

Author: MAGIC Collaboration, Aleksić, J., Alvarez, E. A., Antonelli, L. A., Antoranz, P., Asensio, M., Backes, M., Barrio, J. A., Bastieri, D., González, J. Becerra, Bednarek, W., Berdyugin, A., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnoli, G., Tridon, D. Borla, Braun, I., Bretz, T., Cañellas, A., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Dazzi, F., De Angelis, A., De Caneva, G., del Pozo, E. De Cea, De Lotto, B., Mendez, C. Delgado, Ortega, A. Diago, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Eisenacher, D., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., López, R. J. García, Garczarczyk, M., Garrido, D., Giavitto, G., Godinović, N., Hadasch, D., Häfner, D., Herrero, A., Hildebrand, D., Höhne-Mönch, D., Hose, J., Hrupec, D., Jogler, T., Kellermann, H., Klepser, S., Krähenbühl, T., Krause, J., Kushida, J., La Barbera, A., Lelas, D., Leonardo, E., Lindfors, E., Lombardi, S., López, M., López-Oramas, A., Lorenz, E., Makariev, M., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Moldón, J., Moralejo, A., Munar-Adrover, P., Nieto, D., Nilsson, K., Orito, R., Oya, I., Paneque, D., Paoletti, R., Pardo, S., Paredes, J. M., Partini, S., Perez-Torres, M. A., Persic, M., Peruzzo, L., Pilia, M., Pochon, J., Prada, F., Moroni, P. G. Prada, Prandini, E., Gimenez, I. Puerto, Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rügamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shayduk, M., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Spiro, S., Stamatescu, V., Stamerra, A., Steinke, B., Storz, J., Strah, N., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Tibolla, O., Torres, D. F., Treves, A., Uellenbeck, M., Vankov, H., Vogler, P., Wagner, R. M., Weitzel, Q., Zabalza, V., Zandanel, F., and Zanin, R.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: MAGIC is a system of two Imaging Atmospheric Cherenkov Telescopes located in the Canary island of La Palma. Since autumn 2009 both telescopes have been working together in stereoscopic mode, providing a significant improvement with respect to the previous single-telescope observations. We use observations of the Crab Nebula taken at low zenith angles to assess the performance of the MAGIC stereo system. The trigger threshold of the MAGIC telescopes is 50-60 GeV. Advanced stereo analysis techniques allow MAGIC to achieve a sensitivity as good as (0.76 +/- 0.03)% of the Crab Nebula flux in 50 h of observations above 290 GeV. The angular resolution at those energies is better than ~0.07 degree. We also perform a detailed study of possible systematic effects which may influence the analysis of the data taken with the MAGIC telescopes., Comment: 15 pages, 19 figures, 4 tables, added run-by-run systematics study, and the study of angular resolution as the function of the distance to the camera centre, accepted for publication in Astroparticle Physics
Published: 2011
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197. Revealing the extended radio emission from the gamma-ray binary HESS J0632+057

Author: Moldón, J., Ribó, M., and Paredes, J. M.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Context. After the detection of a 321-days periodicity in X-rays, HESS J0632+057 can be robustly considered a new member of the selected group of gamma-ray binaries. These sources are known to show extended radio structure at scales of milliarcseconds (mas). Aims. We present the expected extended radio emission on mas scales from HESS J0632+057. Methods. We observed HESS J0632+057 with the European VLBI Network (EVN) at 1.6 GHz in two epochs: during the January/February 2011 X-ray outburst and 30 days later. Results. The VLBI image obtained during the outburst shows a compact ~0.4 mJy radio source, whereas 30 days later the source has faded and appears extended, with a projected size of ~75 AU. The peak of the emission is displaced between runs 21+/-5 AU, which is bigger than the orbit size. The position of the radio source is compatible with the Be star MWC 148, which sets the proper motion of the binary system below 3 mas yr^-1 in each coordinate. The brightness temperature of the source is above 2 \times 10^6 K. We compare the multiwavelength properties of HESS J0632+057 with those of the previously known gamma-ray binaries. Conclusions. HESS J0632+057 displays extended and variable non-thermal radio emission. Its morphology, size, and displacement at AU scales are similar to those found in the other gamma-ray binaries, PSR B1259-63, LS 5039 and LS I +61 303, supporting a similar nature for HESS J0632+057., Comment: 5 pages, 2 figures. Updated to match the version published in A&A Letters
Published: 2011
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198. Post-Periastron Gamma Ray Flare from PSR B1259-63/LS 2883 as a Result of Comptonization of the Cold Pulsar Wind

Author: Khangulyan, D., Aharonian, F. A., Bogovalov, S. V., and Ribo, M.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We argue that the bright flare of the binary pulsar \object{PSR B1259$-$63/LS2883} detected by the {\it Fermi} Large Area Telescope (LAT), is due to the inverse Compton (IC) scattering of the unshocked electron-positron pulsar wind with a Lorentz factor $\Gamma_0 \approx 10^4$. The combination of two effects both linked to the circumstellar disk (CD), is a key element in the proposed model. The first effect is related to the impact of the surrounding medium on the termination of the pulsar wind. Inside the disk, the "early" termination of the wind results in suppression of its gamma-ray luminosity. When the pulsar escapes the disk, the conditions for termination of the wind undergo significant changes. This would lead to a dramatic increase of the pulsar wind zone, and thus to the proportional increase of the gamma-ray flux. On the other hand, if the parts of the CD disturbed by the pulsar can supply infrared photons of density high enough for efficient Comptonization of the wind, almost the entire kinetic energy of the pulsar wind would be converted to radiation, thus the gamma-ray luminosity of the wind could approach to the level of the pulsar's spin-down luminosity as reported by the {\it Fermi} collaboration., Comment: 14 pages, 4 figures
Published: 2011
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199. Mrk 421 active state in 2008: the MAGIC view, simultaneous multi-wavelength observations and SSC model constrained

Author: Aleksic, J., Alvarez, E. A., Antonelli, L. A., Antoranz, P., Asensio, M., Backes, M., Barrio, J. A., Bastieri, D., Gonzalez, J. Becerra, Bednarek, W., Berdyugin, A., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnoli, G., Tridon, D. Borla, Braun, I., Bretz, T., Canellas, A., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Dazzi, F., De Angelis, A., De Caneva, G., del Pozo, E. De Cea, De Lotto, B., Mendez, C. Delgado, Ortega, A. Diago, Doert, M., Dominguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., Lopez, R. J. Garcia, Garczarczyk, M., Garrido, D., Giavitto, G., Godinovic, N., Hadasch, D., Häfner, D., Herrero, A., Hildebrand, D., Höhne-Mönch, D., Hose, J., Hrupec, D., Huber, B., Jogler, T., Kellermann, H., Klepser, S., Krahenbuh, T., Krause, J., La Barbera, A., Lelas, D., Leonardo, E., Lindfors, E., Lombardi, S., Lopez, A., Lopez, M., Lorenz, E., Makariev, M., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martinez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Miyamoto, H., Moldon, J., Moralejo, A., Munar-Adrover, P., Nieto, D., Nilsson, K., Orito, R., Oya, I., Paneque, D., Paoletti, R., Pardo, S., Paredes, J. M., Partini, S., Pasanen, M., Pauss, F., Perez-Torres, M. A., Persic, M., Peruzzo, L., Pilia, M., Pochon, J., Prada, F., Moroni, P. G. Prada, Prandini, E., Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribo, M., Rico, J., Rügamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shayduk, M., Shore, S. N., Sillanpaa, A., Sitarek, J., Sobczynska, D., Spanier, F., Spiro, S., Stamerra, A., Steinke, B., Storz, J., Strah, N., Suric, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzic, T., Tescaro, D., Teshima, M., Tibolla, O., Torres, D. F., Treves, A., Uellenbeck, M., Vankov, H., Vogler, P., Wagner, R. M., Weitzel, Q., Zabalza, V., Zandanel, F., and Zanin, R.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Context: The blazar Markarian 421 is one of the brightest TeV gamma-ray sources of the northern sky. From December 2007 until June 2008 it was intensively observed in the very high energy (VHE, E > 100 GeV) band by the single-dish Major Atmospheric Gamma-ray Imaging Cherenkov telescope (MAGIC-I). Aims: We aimed to measure the physical parameters of the emitting region of the blazar jet during active states. Methods: We performed a dense monitoring of the source in VHE with MAGIC-I, and also collected complementary data in soft X-rays and optical-UV bands; then, we modeled the spectral energy distributions (SED) derived from simultaneous multi-wavelength data within the synchrotron self--compton (SSC) framework. Results: The source showed intense and prolonged gamma-ray activity during the whole period, with integral fluxes (E > 200 GeV) seldom below the level of the Crab Nebula, and up to 3.6 times this value. Eight datasets of simultaneous optical-UV (KVA, Swift/UVOT), soft X-ray (Swift/XRT) and MAGIC-I VHE data were obtained during different outburst phases. The data constrain the physical parameters of the jet, once the spectral energy distributions obtained are interpreted within the framework of a single-zone SSC leptonic model. Conclusions: The main outcome of the study is that within the homogeneous model high Doppler factors (40 <= delta <= 80) are needed to reproduce the observed SED; but this model cannot explain the observed short time-scale variability, while it can be argued that inhomogeneous models could allow for less extreme Doppler factors, more intense magnetic fields and shorter electron cooling times compatible with hour or sub-hour scale variability., Comment: 12 pages, 7 figures. Accepted for publication in A&A 7 January 2012
Published: 2011
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200. A search for Very High Energy gamma-ray emission from Scorpius X-1 with the MAGIC telescopes

Author: MAGIC Collaboration, Aleksić, J., Alvarez, E. A., Antonelli, L. A., Antoranz, P., Asensio, M., Backes, M., Barrio, J. A., Bastieri, D., González, J. Becerra, Bednarek, W., Berdyugin, A., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnoli, G., Bordas, P., Tridon, D. Borla, Bosch-Ramon, V., Braun, I., Bretz, T., Cañellas, A., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Dazzi, F., De Angelis, A., del Pozo, E. De Cea, De Lotto, B., Mendez, C. Delgado, Ortega, A. Diago, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., López, R. J. García, Garczarczyk, M., Garrido, D., Giavitto, G., Godinović, N., Hadasch, D., Häfner, D., Herrero, A., Hildebrand, D., Höhne-Mönch, D., Hose, J., Hrupec, D., Huber, B., Jogler, T., Klepser, S., Krähenbühl, T., Krause, J., La Barbera, A., Lelas, D., Leonardo, E., Lindfors, E., Lombardi, S., López, M., Lorenz, E., Makariev, M., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Miyamoto, H., Moldón, J., Moralejo, A., Munar-Adrover, P., Nieto, D., Nilsson, K., Orito, R., Oya, I., Paneque, D., Paoletti, R., Pardo, S., Paredes, J. M., Partini, S., Pasanen, M., Pauss, F., Perez-Torres, M. A., Persic, M., Peruzzo, L., Pilia, M., Pochon, J., Prada, F., Moroni, P. G. Prada, Prandini, E., Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rügamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shayduk, M., Shore, S. N., Sillanpää, A., Sitarek, J., Sobczynska, D., Spanier, F., Spiro, S., Stamerra, A., Steinke, B., Storz, J., Strah, N., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thom, M., Tibolla, O., Torres, D. F., Treves, A., Vankov, H., Vogler, P., Wagner, R. M., Weitzel, Q., Zabalza, V., Zandanel, F., and Zanin, R.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The acceleration of particles up to GeV or higher energies in microquasars has been the subject of considerable theoretical and observational efforts in the past few years. Sco X-1 is a microquasar from which evidence of highly energetic particles in the jet has been found when it is in the so-called Horizontal Branch (HB), a state when the radio and hard X-ray fluxes are higher and a powerful relativistic jet is present. Here we present the first very high energy gamma-ray observations of Sco X-1 obtained with the MAGIC telescopes. An analysis of the whole dataset does not yield a significant signal, with 95% CL flux upper limits above 300 GeV at the level of 2.4x10^{-12} ph/cm^2/s. Simultaneous RXTE observations were conducted to search for TeV emission during particular X-ray states of the source. A selection of the gamma-ray data obtained during the HB based on the X-ray colors did not yield a signal either, with an upper limit of 3.4x10^{-12} ph/cm^2/s. These upper limits place a constraint on the maximum TeV luminosity to non-thermal X-ray luminosity of L_{VHE}/L_{ntX}<0.02, that can be related to a maximum TeV luminosity to jet power ratio of L_{VHE}/L_{j}<10^{-3}. Our upper limits indicate that the underlying high-energy emission physics in Sco X-1 must be inherently different from that of the hitherto detected gamma-ray binaries., Comment: 5 pages, 2 figures, 2 tables. Version as published in ApJL
Published: 2011
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