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268 results on '"Wells, R. M."'

1. A decade of multi-wavelength observations of the TeV blazar 1ES 1215+303: Extreme shift of the synchrotron peak frequency and long-term optical-gamma-ray flux increase

Author

Valverde, Janeth, Horan, Deirdre, Bernard, Denis, Fegan, Stephen, Abeysekara, A. U., Archer, A., Benbow, W., Bird, R., Brill, A., Brose, R., Buchovecky, M., Buckley, J. H., Christiansen, J. L., Cui, W., Falcone, A., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Gent, A., Gillanders, G. H., Giuri, C., Gueta, O., Hanna, D., Hassan, T., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Kaaret, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Lang, M. J., Maier, G., Moriarty, P., Mukherjee, R., Nieto, D., Nievas-Rosillo, M., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pfrang, K., Pichel, A., Pohl, M., Prado, R. R., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Ribeiro, D., Richards, G. T., Roache, E., Sadeh, I., Santander, M., Scott, S. S., Sembroski, G. H., Shahinyan, K., Shang, R., Sushch, I., Vassiliev, V. V., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Williamson, T. J, Noto, Giuliana, Edwards, P. G., Piner, B. G., Ramazani, V. Fallah, Hovatta, T., Jormanainen, J., Lindfors, E., Nilsson, K., Takalo, L., Kovalev, Y. Y., Lister, M. L., Pushkarev, A. B., Savolainen, T., Kiehlmann, S., Max-Moerbeck, W., Readhead, A. C. S., Lähteenmäki, A., and Tornikoski, M.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Blazars are known for their variability on a wide range of timescales at all wavelengths. Most studies of TeV gamma-ray blazars focus on short timescales, especially during flares. With a decade of observations from the Fermi-LAT and VERITAS, we present an extensive study of the long-term multi-wavelength radio-to-gamma-ray flux-density variability, with the addition of a couple of short-time radio-structure and optical polarization observations of the blazar 1ES 1215+303 (z=0.130), with a focus on its gamma-ray emission from 100 MeV to 30 TeV. Multiple strong GeV gamma-ray flares, a long-term increase in the gamma-ray and optical flux baseline and a linear correlation between these two bands are observed over the ten-year period. Typical HBL behaviors are identified in the radio morphology and broadband spectrum of the source. Three stationary features in the innermost jet are resolved by VLBA at 43.1, 22.2, and 15.3 GHz. We employ a two-component synchrotron self-Compton model to describe different flux states of the source, including the epoch during which an extreme shift in energy of the synchrotron peak frequency from infrared to soft X-rays is observed., Comment: Accepted for publication in the Astrophysical Journal

Published
2020
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2. The Great Markarian 421 Flare of February 2010: Multiwavelength variability and correlation studies

Author

Abeysekara, A. U., Benbow, W., Bird, R., Brill, A., Brose, R., Buchovecky, M., Buckley, J. H., Christiansen, J. L., Chromey, A. J., Daniel, M. K., Dumm, J., Falcone, A., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Galante, N., Gent, A., Gillanders, G. H., Giuri, C., Gueta, O., Hassan, T., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Moriarty, P., Mukherjee, R., Nelson, T., Nieto, D., Nievas-Rosillo, M., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pichel, A., Pohl, M., Prado, R. R., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rovero, A. C., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Stevenson, B., Sushch, I., Tyler, J., Vassiliev, V. V., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Zitzer, B., Acciari, V. A., Ansoldi, S., Antonelli, L. A., Engels, A. Arbet, Baack, D., Babić, A., Banerjee, B., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Bellizzi, L., Bernardini, E., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Biland, A., Blanch, O., Bonnoli, G., Busetto, G., Carosi, R., Ceribella, G., Chai, Y., Cikota, S., Colak, S. M., Colin, U., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Di Pierro, F., Espiñera, E. Do Souto, Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Elsaesser, D., Ramazani, V. Fallah, Fattorini, A., Fernández-Barral, A., Ferrara, G., Fidalgo, D., Foffano, L., Fonseca, M. V., Font, L., Fruck, C., Galindo, D., Gallozzi, S., López, R. J. García, Garczarczyk, M., Gasparyan, S., Gaug, M., Godinović, N., Green, D., Guberman, D., Hadasch, D., Hahn, A., Herrera, J., Hoang, J., Hrupec, D., Inoue, S., Ishio, K., Iwamura, Y., Kubo, H., Kushida, J., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Lombardi, S., Longo, F., López, M., López-Coto, R., López-Oramas, A., Fraga, B. Machado de Oliveira, Maggio, C., Majumdar, P., Makariev, M., Mallamaci, M., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Masuda, S., Mazin, D., Miceli, D., Minev, M., Miranda, J. M., Mirzoyan, R., Molina, E., Moralejo, A., Morcuende, D., Moreno, V., Moretti, E., Munar-Adrover, P., Neustroev, V., Niedzwiecki, A., Rosillo, M. Nievas, Nigro, C., Nilsson, K., Ninci, D., Nishijima, K., Noda, K., Nogués, L., Nöthe, M., Paiano, S., Palacio, J., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Peñil, P., Peresano, M., Persic, M., Moroni, P. G. Prada, Prandini, E., Puljak, I., Rhode, W., Ribó, M., Rico, J., Righi, C., Rugliancich, A., Saha, L., Sahakyan, N., Saito, T., Satalecka, K., Schweizer, T., Sitarek, J., Šnidarić, I., Sobczynska, D., Somero, A., Stamerra, A., Strom, D., Strzys, M., Sun, S., Surić, T., Tavecchio, F., Temnikov, P., Terzić, T., Teshima, M., Torres-Albà, N., Tsujimoto, S., van Scherpenberg, J., Vanzo, G., Acosta, M. Vazquez, Vovk, I., Will, M., Zarić, D., Aller, H. D., Aller, M. F., Carini, M. T., Horan, D., Jordan, B., Jorstad, Svetlana G., Kurtanidze, O. M., Kurtanidze, S. O., Lähteenmäki, A., Larionov, V. M., Larionova, E. G., Madejski, G., Marscher, Alan P., Max-Moerbeck, W., Moody, J. Ward, Morozova, D. A., Nikolashvili, M. G., Raiteri, C. M., Readhead, A. C. S., Richards, J. L., Sadun, Alberto C., Sakamoto, T., Sigua, L. A., Smith, P. S., Talvikki, H., Tammi, J., Tornikoski, M., Troitsky, I. S., and Villata, M.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report on variability and correlation studies using multiwavelength observations of the blazar Mrk 421 during the month of February, 2010 when an extraordinary flare reaching a level of $\sim$27~Crab Units above 1~TeV was measured in very-high-energy (VHE) $\gamma$-rays with the VERITAS observatory. This is the highest flux state for Mrk 421 ever observed in VHE $\gamma$-rays. Data are analyzed from a coordinated campaign across multiple instruments including VHE $\gamma$-ray (VERITAS, MAGIC), high-energy (HE) $\gamma$-ray (Fermi-LAT), X-ray (Swift}, RXTE, MAXI), optical (including the GASP-WEBT collaboration and polarization data) and radio (Mets\"ahovi, OVRO, UMRAO). Light curves are produced spanning multiple days before and after the peak of the VHE flare, including over several flare `decline' epochs. The main flare statistics allow 2-minute time bins to be constructed in both the VHE and optical bands enabling a cross-correlation analysis that shows evidence for an optical lag of $\sim$25-55 minutes, the first time-lagged correlation between these bands reported on such short timescales. Limits on the Doppler factor ($\delta \gtrsim 33$) and the size of the emission region ($ \delta^{-1}R_B \lesssim 3.8\times 10^{13}\,\,\mbox{cm}$) are obtained from the fast variability observed by VERITAS during the main flare. Analysis of 10-minute-binned VHE and X-ray data over the decline epochs shows an extraordinary range of behavior in the flux-flux relationship: from linear to quadratic to lack of correlation to anti-correlation. Taken together, these detailed observations of an unprecedented flare seen in Mrk 421 are difficult to explain by the classic single-zone synchrotron self-Compton model., Comment: 41 pages including 3 appendices, 13 figures; version accepted to Astrophysical Journal

Published
2020
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3. Measurement of the extragalactic background light spectral energy distribution with VERITAS

Author

VERITAS collaboration, Abeysekara, A. U., Archer, A., Benbow, W., Bird, R., Brill, A., Brose, R., Buchovecky, M., Christiansen, J. L., Cui, W., Daniel, M. K., Falcone, A., Feng, Q., Fernandez-Alonso, M., Finley, J. P., Fortson, L., Furniss, A., Gent, A., Giuri, C., Gueta, O., Hanna, D., Hassan, T., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Maier, G., Moriarty, P., Mukherjee, R., Nievas-Rosillo, M., O'Brien, S., Ong, R. A., Pfrang, K., Pohl, M., Prado, R. R., Pueschel, E., Ragan, K., Reynolds, P. T., Ribeiro, D., Richards, G. T., Roache, E., Rovero, A. C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Sushch, I., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Williamson, T. J, and Zitzer, B.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The extragalactic background light (EBL), a diffuse photon field in the optical and infrared range, is a record of radiative processes over the Universe's history. Spectral measurements of blazars at very high energies ($>$100 GeV) enable the reconstruction of the spectral energy distribution (SED) of the EBL, as the blazar spectra are modified by redshift- and energy-dependent interactions of the gamma-ray photons with the EBL. The spectra of 14 VERITAS-detected blazars are included in a new measurement of the EBL SED that is independent of EBL SED models. The resulting SED covers an EBL wavelength range of 0.56--56 $\mu$m, and is in good agreement with lower limits obtained by assuming that the EBL is entirely due to radiation from cataloged galaxies., Comment: Accepted for publication in The Astrophysical Journal

Published
2019
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4. VERITAS contributions to the 36th International Cosmic Ray Conference

Author

Abeysekara, A. U., Archer, A., Benbow, W., Bird, R., Brill, A., Brose, R., Buckley, J. H., Christiansen, J. L., Chromey, A. J., Daniel, M. K., Das, S., Falcone, A., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Gent, A., Gillanders, G. H., Giuri, C., Gueta, O., Hanna, D., Hassan, T., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Kaaret, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krause, M., Kumar, S., Lang, M. J., Lin, T. T. Y., Lundy, M., Maier, G., Matthews, N., Moriarty, P., Mukherjee, R., Nievas-Rosillo, M., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pfrang, K., Pohl, M., Prado, R. R., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Ribeiro, D., Richards, G. T., Roache, E., Sadeh, I., Santander, M., Schlenstedt, S., Scott, S. S., Sembroski, G. H., Shang, R., Vassiliev, V. V., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Williams, D. A., and Williamson, T. J

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Compilation of papers presented by the VERITAS Collaboration at the 36th International Cosmic Ray Conference (ICRC), held July 24 through August 1, 2019 in Madison, Wisconsin., Comment: html page. 2019 ICRC, Madison, Wisconsin

Published
2019

5. A Search for Pulsed Very High-Energy Gamma Rays from Thirteen Young Pulsars in Archival VERITAS Data

Author

Archer, A., Benbow, W., Bird, R., Brose, R., Buchovecky, M., Buckley, J. H., Chromey, A. J., Cui, W., Falcone, A., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Gent, A., Gueta, O., Hanna, D., Hassan, T., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krennrich, F., Kumar, S., Lang, M. J., Lin, T. T. Y., McCann, A., Moriarty, P., Mukherjee, R., O'Brien, S., Ong, R. A., Otte, A. N., Pandel, D., Park, N., Petrashyk, A., Pohl, M., Pueschel, E., Quinn, J., Ragan, K., Richards, G. T., Roache, E., Sadeh, I., Santander, M., Scott, S. S., Sembroski, G. H., Shahinyan, K., Sushch, I., Tyler, J., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Williamson, T. J, and Zitzer, B.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We conduct a search for periodic emission in the very high-energy gamma-ray band (VHE; E > 100 GeV) from a total of 13 pulsars in an archival VERITAS data set with a total exposure of over 450 hours. The set of pulsars includes many of the brightest young gamma-ray pulsars visible in the Northern Hemisphere. The data analysis resulted in non-detections of pulsed VHE gamma rays from each pulsar. Upper limits on a potential VHE gamma-ray flux are derived at the 95% confidence level above three energy thresholds using two methods. These are the first such searches for pulsed VHE emission from each of the pulsars, and the obtained limits constrain a possible flux component manifesting at VHEs as is seen for the Crab pulsar., Comment: 32 pages, 20 figures, accepted for publication in ApJ

Published
2019
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6. Direct measurement of stellar angular diameters by the VERITAS Cherenkov Telescopes

Author

Benbow, W., Bird, R., Brill, A., Brose, R., Chromey, A. J., Daniel, M. K., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Gillanders, G. H., Giuri, C., Gueta, O., Hanna, D., Halpern, J., Hassan, T., Holder, J., Hughes, G., Humensky, T. B., Joyce, A. M., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krause, M., Lang, M. J., Lin, T. T. Y., Maier, G., Matthews, N., Moriarty, P., Mukherjee, R., Nieto, D., Nievas-Rosillo, M., O'Brien, S., Ong, R. A., Park, N., Petrashyk, A., Pohl, M., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Sushch, I., Wakely, S. P., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., and Williamson, T. J.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

The angular size of a star is a critical factor in determining its basic properties. Direct measurement of stellar angular diameters is difficult: at interstellar distances stars are generally too small to resolve by any individual imaging telescope. This fundamental limitation can be overcome by studying the diffraction pattern in the shadow cast when an asteroid occults a star, but only when the photometric uncertainty is smaller than the noise added by atmospheric scintillation. Atmospheric Cherenkov telescopes used for particle astrophysics observations have not generally been exploited for optical astronomy due to the modest optical quality of the mirror surface. However, their large mirror area makes them well suited for such high-time-resolution precision photometry measurements. Here we report two occultations of stars observed by the VERITAS Cherenkov telescopes with millisecond sampling, from which we are able to provide a direct measurement of the occulted stars' angular diameter at the $\leq0.1$ milliarcsecond scale. This is a resolution never achieved before with optical measurements and represents an order of magnitude improvement over the equivalent lunar occultation method. We compare the resulting stellar radius with empirically derived estimates from temperature and brightness measurements, confirming the latter can be biased for stars with ambiguous stellar classifications., Comment: Accepted for publication in Nature Astronomy

Published
2019
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7. Periastron Observations of TeV Gamma-Ray Emission from a Binary System with a 50-year Period

Author

The VERITAS Collaboration, Abeysekara, A. U., Benbow, W., Bird, R., Brill, A., Brose, R., Buckley, J. H., Chromey, A. J., Daniel, M. K., Falcone, A., Finley, J. P., Fortson, L., Furniss, A., Gent, A., Gillanders, G. H., Hanna, D., Hassan, T., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Kaaret, P., Kar, P., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Lin, T. T. Y., Maier, G., Moriarty, P., Mukherjee, R., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pohl, M., Pueschel, E., Quinn, J., Ragan, K., Richards, G. T., Roache, E., Sadeh, I., Santander, M., Schlenstedt, S., Sembroski, G. H., Sushch, I., Tyler, J., Vassiliev, V. V., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Williamson, T. J, Zitzer, B., Collaboration, MAGIC, Acciari, V. A., Ansoldi, S., Antonelli, L. A., Engels, A. Arbet, Baack, D., Babić, A., Banerjee, B., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Bernardini, E., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Biland, A., Blanch, O., Bonnoli, G., Busetto, G., Carosi, R., Ceribella, G., Cikota, S., Colak, S. M., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Di Pierro, F., Espiñera, E. Do Souto, Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Elsaesser, D., Ramazani, V. Fallah, Fattorini, A., Fernández-Barral, A., Ferrara, G., Fidalgo, D., Foffano, L., Fonseca, M. V., Font, L., Fruck, C., Galindo, D., Gallozzi, S., López, R. J. García, Garczarczyk, M., Gasparyan, S., Gaug, M., Giammaria, P., Godinović, N., Guberman, D., Hadasch, D., Hahn, A., Herrera, J., Hoang, J., Hrupec, D., Inoue, S., Ishio, K., Iwamura, Y., Kubo, H., Kushida, J., Kuveždić, D., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Lombardi, S., Longo, F., López, M., López-Oramas, A., Fraga, B. Machado de Oliveira, Maggio, C., Majumdar, P., Makariev, M., Mallamaci, M., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Masuda, S., Mazin, D., Minev, M., Miranda, J. M., Mirzoyan, R., Molina, E., Moralejo, A., Moreno, V., Moretti, E., Munar-Adrover, P., Neustroev, V., Niedzwiecki, A., Rosillo, M. Nievas, Nigro, C., Nilsson, K., Ninci, D., Nishijima, K., Noda, K., Nogués, L., Nöthe, M., Paiano, S., Palacio, J., Paneque, D., Paoletti, R., Paredes, J. M., Pedaletti, G., Peñil, P., Peresano, M., Persic, M., Moroni, P. G. Prada, Prandini, E., Puljak, I., Garcia, J. R., Rhode, W., Ribó, M., Rico, J., Righi, C., Rugliancich, A., Saha, L., Sahakyan, N., Saito, T., Satalecka, K., Schweizer, T., Sitarek, J., Šnidarić, I., Sobczynska, D., Somero, A., Stamerra, A., Strzys, M., Surić, T., Tavecchio, F., Temnikov, P., Terzić, T., Teshima, M., Torres-Albà, N., Tsujimoto, S., van Scherpenberg, J., Vanzo, G., Acosta, M. Vazquez, Vovk, I., Will, M., and Zarić, D.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report on observations of the pulsar / Be star binary system PSR J2032+4127 / MT91 213 in the energy range between 100 GeV and 20 TeV with the VERITAS and MAGIC imaging atmospheric Cherenkov telescope arrays. The binary orbit has a period of approximately 50 years, with the most recent periastron occurring on 2017 November 13. Our observations span from 18 months prior to periastron to one month after. A new, point-like, gamma-ray source is detected, coincident with the location of PSR J2032+4127 / MT91 213. The gamma-ray light curve and spectrum are well-characterized over the periastron passage. The flux is variable over at least an order of magnitude, peaking at periastron, thus providing a firm association of the TeV source with the pulsar / Be star system. Observations prior to periastron show a cutoff in the spectrum at an energy around 0.5 TeV. This result adds a new member to the small population of known TeV binaries, and it identifies only the second source of this class in which the nature and properties of the compact object are firmly established. We compare the gamma-ray results with the light curve measured with the X-ray Telescope (XRT) on board the Neil Gehrels \textit{Swift} Observatory and with the predictions of recent theoretical models of the system. We conclude that significant revision of the models is required to explain the details of the emission we have observed, and we discuss the relationship between the binary system and the overlapping steady extended source, TeV J2032+4130., Comment: 12 pages, 3 figures, 1 table. Accepted for publication in ApJL

Published
2018
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8. VERITAS and Fermi-LAT observations of new HAWC sources

Author

VERITAS Collaboration, Abeysekara, A. U., Archer, A., Benbow, W., Bird, R., Brose, R., Buchovecky, M., Buckley, J. H., Bugaev, V., Chromey, A. J., Connolly, M. P., Cui, W., Daniel, M. K., Falcone, A., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Hutten, M., Hanna, D., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Lin, T. T. Y., McArthur, S., Moriarty, P., Mukherjee, R., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pohl, M., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Sushch, I., Tyler, J., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Williamson, T. J., Zitzer, B., Collaboration, Fermi-LAT, Abdollahi, S., Ajello, M., Baldini, L., Barbiellini, G., Bastieri, D., Bellazzini, R., Berenji, B., Bissaldi, E., Blandford, R. D., Bonino, R., Bottacini, E., Brandt, T. J., Bruel, P., Buehler, R., Cameron, R. A., Caputo, R., Caraveo, P. A., Castro, D., Cavazzuti, E., Charles, E., Chiaro, G., Ciprini, S., Cohen-Tanugi, J., Costantin, D., Cutini, S., D'Ammando, F., de Palma, F., Di Lalla, N., Di Mauro, M., Di Venere, L., Dominguez, A., Favuzzi, C., Fegan, S. J., Franckowiak, A., Fukazawa, Y., Funk, S., Fusco, P., Gargano, F., Gasparrini, D., Giglietto, N., Giordano, F., Giroletti, M., Green, D., Grenier, I. A., Guillemot, L., Guiriec, S., Hays, E., Hewitt, J. W., Horan, D., Johannesson, G., Kensei, S., Kuss, M., Larsson, S., Latronico, L., Lemoine-Goumard, M., Li, J., Longo, F., Loparco, F., Lovellette, M. N., Lubrano, P., Magill, J. D., Maldera, S., Mazziotta, M. N., McEnery, J. E., Michelson, P. F., Mitthumsiri, W., Mizuno, T., Monzani, M. E., Morselli, A., Moskalenko, I. V., Negro, M., Nuss, E., Ojha, R., Omodei, N., Orienti, M., Orlando, E., Palatiello, M., Paliya, V. S., Paneque, D., Perkins, J. S., Persic, M., Pesce-Rollins, M., Petrosian, V., Piron, F., Porter, T. A., Principe, G., Raino, S., Rando, R., Rani, B., Razzano, M., Razzaque, S., Reimer, A., Reimer, O., Reposeur, T., Sgro, C., Siskind, E. J., Spandre, G., Spinelli, P., Suson, D. J., Tajima, H., Thayer, J. B., Thompson, D. J., Torres, D. F., Tosti, G., Troja, E., Valverde, J., Vianello, G., Vogel, M., Wood, K., Yassine, M., Collaboration, HAWC, Alfaro, R., Alvarez, C., Alvarez, J. D., Arceo, R., Arteaga-Velazquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Becerril, A., Belmont-Moreno, E., BenZvi, S. Y., Bernal, A., Braun, J., Brisbois, C., Caballero-Mora, K. S., Capistran, T., Carraminana, A., Casanova, S., Castillo, M., Cotti, U., Cotzomi, J., de Leon, S. Coutino, De Leon, C., De la Fuente, E., Dichiara, S., Dingus, B. L., DuVernois, M. A., Diaz-Velez, J. C., Engel, K., Enriquez-Rivera, O., Fiorino, D. W., Fleischhack, H., Fraija, N., Garcia-Gonzalez, J. A., Garfias, F., Munoz, A. Gonzalez, Gonzalez, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hernandez-Almada, A., Hona, B., Hueyotl-Zahuantitla, F., Hui, C. M., Huntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. Leon, Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Luna-Garcia, R., Lopez-Coto, R., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martinez-Castro, J., Martinez-Huerta, H., Matthews, J. A., Miranda-Romagnoli, P., Moreno, E., Mostafa, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pelayo, R., Pretz, J., Perez-Perez, E. G., Ren, Z., Rho, C. D., Riviere, C., Rosa-Gonzalez, D., Rosenberg, M., Ruiz-Velasco, E., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Arroyo, M. Seglar, Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Taboada, I., Tibolla, O., Tollefson, K., Torres, I., Ukwatta, T. N., Villasenor, L., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yapici, T., Yodh, G., Zepeda, A., and Zhou, H.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The HAWC (High Altitude Water Cherenkov) collaboration recently published their 2HWC catalog, listing 39 very high energy (VHE; >100~GeV) gamma-ray sources based on 507 days of observation. Among these, there are nineteen sources that are not associated with previously known TeV sources. We have studied fourteen of these sources without known counterparts with VERITAS and Fermi-LAT. VERITAS detected weak gamma-ray emission in the 1~TeV-30~TeV band in the region of DA 495, a pulsar wind nebula coinciding with 2HWC J1953+294, confirming the discovery of the source by HAWC. We did not find any counterpart for the selected fourteen new HAWC sources from our analysis of Fermi-LAT data for energies higher than 10 GeV. During the search, we detected GeV gamma-ray emission coincident with a known TeV pulsar wind nebula, SNR G54.1+0.3 (VER J1930+188), and a 2HWC source, 2HWC J1930+188. The fluxes for isolated, steady sources in the 2HWC catalog are generally in good agreement with those measured by imaging atmospheric Cherenkov telescopes. However, the VERITAS fluxes for SNR G54.1+0.3, DA 495, and TeV J2032+4130 are lower than those measured by HAWC and several new HAWC sources are not detected by VERITAS. This is likely due to a change in spectral shape, source extension, or the influence of diffuse emission in the source region., Comment: Accepted for publication in the ApJ, Corresponding author: Nahee Park (VERITAS Collaboration), John W. Hewitt (Fermi-LAT Collaboration), Ignacio Taboada (HAWC Collaboration), 30 pages, 12 figures

Published
2018
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9. Measurement of Cosmic-ray Electrons at TeV Energies by VERITAS

Author

VERITAS Collaboration, Archer, A., Benbow, W., Bird, R., Brose, R., Buchovecky, M., Buckley, J. H., Bugaev, V., Connolly, M. P., Cui, W., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Gillanders, G., Hütten, M., Hanna, D., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Lin, T. T. Y., Maier, G., McArthur, S., Moriarty, P., Mukherjee, R., O'Brien, S., Ong, R. A., Otte, A. N., Petrashyk, A., Pohl, M., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Staszak, D., Sushch, I., Tyler, J., Wakely, S. P., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Williamson, T. J, and Zitzer, B.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Cosmic-ray electrons and positrons (CREs) at GeV-TeV energies are a unique probe of our local Galactic neighborhood. CREs lose energy rapidly via synchrotron radiation and inverse-Compton scattering processes while propagating within the Galaxy and these losses limit their propagation distance. For electrons with TeV energies, the limit is on the order of a kiloparsec. Within that distance there are only a few known astrophysical objects capable of accelerating electrons to such high energies. It is also possible that the CREs are the products of the annihilation or decay of heavy dark matter (DM) particles. VERITAS, an array of imaging air Cherenkov telescopes in southern Arizona, USA, is primarily utilized for gamma-ray astronomy, but also simultaneously collects CREs during all observations. We describe our methods of identifying CREs in VERITAS data and present an energy spectrum, extending from 300 GeV to 5 TeV, obtained from approximately 300 hours of observations. A single power-law fit is ruled out in VERITAS data. We find that the spectrum of CREs is consistent with a broken power law, with a break energy at 710 $\pm$ 40$_{stat}$ $\pm$ 140$_{syst}$ GeV., Comment: 17 pages, 2 figures, accepted for publication in PRD

Published
2018
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10. The extreme HBL behaviour of Markarian 501 during 2012

Author

Ahnen, M. L., Ansoldi, S., Antonelli, L. A., Arcaro, C., Babić, A., Banerjee, B., Bangale, P., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Bernardini, E., Berti, A., Bhattacharyya, W., Blanch, O., Bonnoli, G., Carosi, R., Carosi, A., Chatterjee, A., Colak, S. M., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Cumani, P., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Di Pierro, F., Doert, M., Domínguez, A., Prester, D. Dominis, Doro, M., Glawion, D. Eisenacher, Engelkemeier, M., Ramazani, V. Fallah, Fernández-Barral, A., Fidalgo, D., Fonseca, M. V., Font, L., Fruck, C., Galindo, D., López, R. J. García, Garczarczyk, M., Gaug, M., Giammaria, P., Godinović, N., Gora, D., Guberman, D., Hadasch, D., Hahn, A., Hassan, T., Hayashida, M., Herrera, J., Hose, J., Hrupec, D., Ishio, K., Konno, Y., Kubo, H., Kushida, J., Kuveždić, D., Lelas, D., Lindfors, E., Lombardi, S., Longo, F., López, M., Maggio, C., Majumdar, P., Makariev, M., Maneva, G., Manganaro, M., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Minev, M., Miranda, J. M., Mirzoyan, R., Moralejo, A., Moreno, V., Moretti, E., Nagayoshi, T., Neustroev, V., Niedzwiecki, A., Rosillo, M. Nievas, Nigro, C., Nilsson, K., Ninci, D., Nishijima, K., Noda, K., Nogués, L., Paiano, S., Palacio, J., Paneque, D., Paoletti, R., Paredes, J. M., Pedaletti, G., Peresano, M., Perri, L., Persic, M., Moroni, P. G. Prada, Prandini, E., Puljak, I., Garcia, J. R., Reichardt, I., Ribó, M., Rico, J., Righi, C., Rugliancich, A., Saito, T., Satalecka, K., Schroeder, S., Schweizer, T., Shore, S. N., Sitarek, J., Šnidarić, I., Sobczynska, D., Stamerra, A., Strzys, M., Surić, T., Takalo, L., Tavecchio, F., Temnikov, P., Terzić, T., Teshima, M., Torres-Albà, N., Treves, A., Tsujimoto, S., Vanzo, G., Acosta, M. Vazquez, Vovk, I., Ward, J. E., Will, M., Zarić, D., Arbet-Engels, A., Baack, D., Balbo, M., Biland, A., Blank, M., Bretz, T., Bruegge, K., Bulinski, M., Buss, J., Dmytriiev, A., Dorner, D., Einecke, S., Elsaesser, D., Herbst, T., Hildebrand, D., Kortmann, L., Linhoff, L., Mahlke, M., Mannheim, K., Mueller, S. A., Neise, D., Neronov, A., Noethe, M., Oberkirch, J., Paravac, A., Rhode, W., Schleicher, B., Schulz, F., Sedlaczek, K., Shukla, A., Sliusar, V., Walter, R., Archer, A., Benbow, W., Bird, R., Brose, R., Buckley, J. H., Bugaev, V., Christiansen, J. L., Cui, W., Daniel, M. K., Falcone, A., Feng, Q., Finley, J. P., Gillanders, G. H., Gueta, O., Hanna, D., Hervet, O., Holder, J., Hughes, G., Hütten, M., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Lin, T. T. Y., Maier, G., McArthur, S., Moriarty, P., Mukherjee, R., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pichel, A., Pohl, M., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rovero, A. C., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Sushch, I., Tyler, J., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Wilhel, A., Williams, D. A., Williamson, T. J, Zitzer, B., Perri, M., Verrecchia, F., Leto, C., Villata, M., Raiteri, C. M., Jorstad, S. G., Larionov, V. M., Blinov, D. A., Grishina, T. S., Kopatskaya, E. N., Larionova, E. G., Nikiforova, A. A., Morozova, D. A., Troitskaya, Yu. V., Troitsky, I. S., Kurtanidze, O. M., Nikolashvili, M. G., Kurtanidze, S. O., Kimeridze, G. N., Chigladze, R. A., Strigachev, A., Sadun, A. C., Moody, J. W., Chen, W. P., Lin, H. C., Acosta-Pulido, J. A., Arévalo, M. J., Carnerero, M. I., González-Morales, P. A., Manilla-Robles, A., Jermak, H., Steele, I., Mundel, C., Benítez, E., Hiriart, D., Smith, P. S., Max-Moerbeck, W., Readhead, A. C. S., Richards, J. L., Hovatta, T., Lähteenmäki, A., Tornikoski, M., Tammi, J., Georganopoulos, M., and Baring, M. G.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

A multiwavelength campaign was organized to take place between March and July of 2012. Excellent temporal coverage was obtained with more than 25 instruments, including the MAGIC, FACT and VERITAS Cherenkov telescopes, the instruments on board the Swift and Fermi spacecraft, and the telescopes operated by the GASP-WEBT collaboration. Mrk 501 showed a very high energy (VHE) gamma-ray flux above 0.2 TeV of $\sim$0.5 times the Crab Nebula flux (CU) for most of the campaign. The highest activity occurred on 2012 June 9, when the VHE flux was $\sim$3 CU, and the peak of the high-energy spectral component was found to be at $\sim$2 TeV. This study reports very hard X-ray spectra, and the hardest VHE spectra measured to date for Mrk 501. The fractional variability was found to increase with energy, with the highest variability occurring at VHE, and a significant correlation between the X-ray and VHE bands. The unprecedentedly hard X-ray and VHE spectra measured imply that their low- and high-energy components peaked above 5 keV and 0.5 TeV, respectively, during a large fraction of the observing campaign, and hence that Mrk 501 behaved like an extreme high-frequency- peaked blazar (EHBL) throughout the 2012 observing season. This suggests that being an EHBL may not be a permanent characteristic of a blazar, but rather a state which may change over time. The one-zone synchrotron self-Compton (SSC) scenario can successfully describe the segments of the SED where most energy is emitted, with a significant correlation between the electron energy density and the VHE gamma-ray activity, suggesting that most of the variability may be explained by the injection of high-energy electrons. The one-zone SSC scenario used reproduces the behaviour seen between the measured X-ray and VHE gamma-ray fluxes, and predicts that the correlation becomes stronger with increasing energy of the X-rays., Comment: 25 pages, 9 figures, accepted for publication in A&A. Corresponding authors: Gareth Hughes (gareth.hughes@cfa.harvard.edu), David Paneque (dpaneque@mppmu.mpg.de), Amit Shukla (amit.shukla@astro.uni-wuerzburg.de)

Published
2018
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11. VERITAS observations of the BL Lac object TXS 0506+056

Author

Abeysekara, A. U., Archer, A., Benbow, W., Bird, R., Brill, A., Brose, R., Buckley, J. H., Christiansen, J. L., Chromey, A. J., Daniel, M. K., Falcone, A., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Gillanders, G. H., Gueta, O., Hanna, D., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Lang, M. J., Moriarty, P., Mukherjee, R., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pohl, M., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rulten, C., Sadeh, I., Santander, M., Scott, S. S., Sembroski, G. H., Shahinyan, K., Tyler, J., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Williamson, T. J, and Zitzer, B.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

On 2017 September 22, the IceCube Neutrino Observatory reported the detection of the high-energy neutrino event \icnu, of potential astrophysical origin. It was soon determined that the neutrino direction was consistent with the location of the gamma-ray blazar \txs~(3FGL J0509.4+0541), which was in an elevated gamma-ray emission state as measured by the \emph{Fermi} satellite. VERITAS observations of the neutrino/blazar region started on 2017 September 23 in response to the neutrino alert and continued through 2018 February 6. While no significant very-high-energy (VHE; E $>$ 100 GeV) emission was observed from the blazar by VERITAS in the two-week period immediately following the IceCube alert, TXS 0506+056 was detected by VERITAS with a significance of 5.8 standard deviations ($\sigma$) in the full 35-hour data set. The average photon flux of the source during this period was $(8.9 \pm 1.6) \times 10^{-12} \; \mathrm{cm}^{-2} \, \mathrm{s}^{-1}$, or 1.6\% of the Crab Nebula flux, above an energy threshold of 110 GeV, with a soft spectral index of $4.8 \pm 1.3$.

Published
2018
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12. HESS J1943+213: An Extreme Blazar Shining Through The Galactic Plane

Author

The VERITAS Collaboration, Archer, A., Benbow, W., Bird, R., Brose, R., Buchovecky, M., Bugaev, V., Cui, W., Daniel, M. K., Falcone, A., Feng, Q., Finley, J. P., Flinders, A., Fortson, L., Furniss, A., Gillanders, G. H., Hütten, M., Hanna, D., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Lin, T. T. Y., McArthur, S., Moriarty, P., Mukherjee, R., Nieto, D., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pohl, M., Popkow, A., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rulten, C., Sadeh, I., Sembroski, G. H., Shahinyan, K., Tyler, J., Wakely, S. P., Weiner, O. M., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Brisken, W. F., and Pontrelli, P.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

HESS J1943+213 is a very-high-energy (VHE; $>$100 GeV) $\gamma$-ray source in the direction of the Galactic Plane. Studies exploring the classification of the source are converging towards its identification as an extreme synchrotron BL Lac object. Here we present 38 hours of VERITAS observations of HESS J1943+213 taken over two years. The source is detected with $\sim$20 standard deviations significance, showing a remarkably stable flux and spectrum in VHE $\gamma$-rays. Multi-frequency very-long-baseline array (VLBA) observations of the source confirm the extended, jet-like structure previously found in the 1.6 GHz band with European VLBI Network and detect this component in the 4.6 GHz and the 7.3 GHz bands. The radio spectral indices of the core and the jet and the level of polarization derived from the VLBA observations are in a range typical for blazars. Data from VERITAS, $Fermi$-LAT, $Swift$-XRT, FLWO 48$''$ telescope, and archival infrared and hard X-ray observations are used to construct and model the spectral energy distribution (SED) of the source with a synchrotron-self-Compton model. The well-measured $\gamma$-ray peak of the SED with VERITAS and $Fermi$-LAT provides constraining upper limits on the source redshift. Possible contribution of secondary $\gamma$-rays from ultra-high-energy cosmic ray-initiated electromagnetic cascades to the $\gamma$-ray emission is explored, finding that only a segment of the VHE spectrum can be accommodated with this process. A variability search is performed across X-ray and $\gamma$-ray bands. No statistically significant flux or spectral variability is detected., Comment: Accepted for publication in The Astrophysical Journal

Published
2018
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13. A Very High Energy $\gamma$-Ray Survey towards the Cygnus Region of the Galaxy

Author

The VERITAS Collaboration, Abeysekara, A. U., Archer, A., Aune, T., Benbow, W., Bird, R., Brose, R., Buchovecky, M., Bugaev, V., Cui, W., Daniel, M. K., Falcone, A., Feng, Q., Finley, J. P., Fleischhack, H., Flinders, A., Fortson, L., Furniss, A., Gotthelf, E. V., Grube, J., Hanna, D., Hervet, O., Holder, J., Huang, K., Hughes, G., Humensky, T. B., Hütten, M., Johnson, C. A., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krause, M., Kumar, S., Lang, M. J., Lin, T. T. Y., Maier, G., McArthur, S., Moriarty, P., Mukherjee, R., O'Brien, S., Ong, R. A., Otte, A. N., Pandel, D., Park, N., Petrashyk, A., Pohl, M., Popkow, A., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rousselle, J., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Tyler, J., Vassiliev, V. V., Wakely, S. P., Ward, J. E., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., and Zitzer, B.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present results from deep observations towards the Cygnus region using 300 hours of very-high-energy (VHE) $\gamma$-ray data taken with the VERITAS Cherenkov telescope array and over seven years of high-energy $\gamma$-ray data taken with the Fermi satellite at an energy above 1 GeV. As the brightest region of diffuse $\gamma$-ray emission in the northern sky, the Cygnus region provides a promising area to probe the origins of cosmic rays. We report the identification of a potential Fermi-LAT counterpart to VER J2031+415 (TeV J2032+4130), and resolve the extended VHE source VER J2019+368 into two source candidates (VER J2018+367* and VER J2020+368*) and characterize their energy spectra. The Fermi-LAT morphology of 3FGL 2021.0+4031e (the Gamma-Cygni supernova remnant) was examined and a region of enhanced emission coincident with VER J2019+407 was identified and jointly fit with the VERITAS data. By modeling 3FGL J2015.6+3709 as two sources, one located at the location of the pulsar wind nebula CTB 87 and one at the quasar QSO J2015+371, a continuous spectrum from 1 GeV to 10 TeV was extracted for VER J2016+371 (CTB 87). An additional 71 locations coincident with Fermi-LAT sources and other potential objects of interest were tested for VHE $\gamma$-ray emission, with no emission detected and upper limits on the differential flux placed at an average of 2.3% of the Crab Nebula ux. We interpret these observations in a multiwavelength context and present the most detailed $\gamma$-ray view of the region to date., Comment: 49 Pages, 22 Figures, 13 Tables, Accepted to ApJ

Published
2018
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14. A strong limit on the very-high-energy emission from GRB 150323A

Author

Abeysekara, A. U., Archer, A., Benbow, W., Bird, R., Brose, R., Buchovecky, M., Bugaev, V., Connolly, M. P., Cui, W., Errando, M., Falcone, A., Feng, Q., Finley, J. P., Flinders, A., Fortson, L., Furniss, A., Gillanders, G. H., Hütten, M., Hanna, D., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Lang, M. J., Lin, T. T. Y., Maier, G., McArthur, S., Moriarty, P., Mukherjee, R., O'Brien, S., Ong, R. A., Park, N., Perkins, J. S., Petrashyk, A., Pohl, M., Popkow, A., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Tyler, J., Wakely, S. P., Weiner, O. M., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Zitzer, B., Vurm, Indrek, and Beloborodov, Andrei

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

On 2015 March 23, VERITAS responded to a $Swift$-BAT detection of a gamma-ray burst, with observations beginning 270 seconds after the onset of BAT emission, and only 135 seconds after the main BAT emission peak. No statistically significant signal is detected above 140 GeV. The VERITAS upper limit on the fluence in a 40 minute integration corresponds to about 1% of the prompt fluence. Our limit is particularly significant since the very-high-energy (VHE) observation started only $\sim$2 minutes after the prompt emission peaked, and $Fermi$-LAT observations of numerous other bursts have revealed that the high-energy emission is typically delayed relative to the prompt radiation and lasts significantly longer. Also, the proximity of GRB~150323A ($z=0.593$) limits the attenuation by the extragalactic background light to $\sim 50$ % at 100-200 GeV. We conclude that GRB 150323A had an intrinsically very weak high-energy afterglow, or that the GeV spectrum had a turnover below $\sim100$ GeV. If the GRB exploded into the stellar wind of a massive progenitor, the VHE non-detection constrains the wind density parameter to be $A\gtrsim 3\times 10^{11}$ g cm$^{-1}$, consistent with a standard Wolf-Rayet progenitor. Alternatively, the VHE emission from the blast wave would be weak in a very tenuous medium such as the ISM, which therefore cannot be ruled out as the environment of GRB 150323A., Comment: 6 pages, 1 figure. Accepted for publication in The Astrophysical Journal

Published
2018
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15. Multiwavelength observations of the blazar BL Lacertae: a new fast TeV gamma-ray flare

Author

Abeysekara, A. U., Benbow, W., Bird, R., Brantseg, T., Brose, R., Buchovecky, M., Buckley, J. H., Bugaev, V., Connolly, M. P., Cui, W., Daniel, M. K., Falcone, A., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Gillanders, G. H., Gunawardhana, I., Hütten, M., Hanna, D., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kertzman, M., Krennrich, F., Lang, M. J., Lin, T. T. Y., McArthur, S., Moriarty, P., Mukherjee, R., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pohl, M., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Williams, D. A., Zitzer, B., Jorstad, S. G., Marscher, A. P., Lister, M. L., Kovalev, Y. Y., Pushkarev, A. B., Savolainen, T., Agudo, I., Molina, S. N., Gómez, J. L., Larionov, V. M., Borman, G. A., Mokrushina, A. A., Tornikoski, M., Lähteenmäki, A., Chamani, W., Enestam, S., Kiehlmann, S., Hovatta, T., Smith, P. S., and Pontrelli, P.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Combined with very-long-baseline interferometry measurements, the observations of fast TeV gamma-ray flares probe the structure and emission mechanism of blazar jets. However, only a handful of such flares have been detected to date, and only within the last few years have these flares been observed from lower-frequency-peaked BL~Lac objects and flat-spectrum radio quasars. We report on a fast TeV gamma-ray flare from the blazar BL~Lacertae observed by VERITAS, with a rise time of $\sim$2.3~hr and a decay time of $\sim$36~min. The peak flux above 200 GeV is $(4.2 \pm 0.6) \times 10^{-6} \;\text{photon} \;\text{m}^{-2}\; \text{s}^{-1}$ measured with a 4-minute-binned light curve, corresponding to $\sim$180\% of the flux which is observed from the Crab Nebula above the same energy threshold. Variability contemporaneous with the TeV gamma-ray flare was observed in GeV gamma-ray, X-ray, and optical flux, as well as in optical and radio polarization. Additionally, a possible moving emission feature with superluminal apparent velocity was identified in VLBA observations at 43 GHz, potentially passing the radio core of the jet around the time of the gamma-ray flare. We discuss the constraints on the size, Lorentz factor, and location of the emitting region of the flare, and the interpretations with several theoretical models which invoke relativistic plasma passing stationary shocks., Comment: 23 pages, 9 figures

Published
2018
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16. VERITAS contributions to the 35th International Cosmic Ray Conference

Author

Abeysekara, A. U., Archambault, S., Archer, A., Benbow, W., Bird, R., Brose, R., Buchovecky, M., Christiansen, J. L., Connolly, M. P., Cui, W., Daniel, M. K., Falcone, A., Feng, Q., Fernandez-Alonso, M., Finley, J. P., Fleischhack, H., Fortson, L., Furniss, A., Gillanders, G. H., Hütten, M., Hanna, D., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Maier, G., McArthur, S., Moriarty, P., Mukherjee, R., Nieto, D., O'Brien, S., Ong, R. A., Otte, A. N., Pandel, D., Park, N., Pohl, M., Popkow, A., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Roache, E., Rovero, A. C., Sadeh, I., Santander, M., Schlenstedt, S., Sembroski, G. H., Shahinyan, K., Tyler, J., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Williamson, T. J, and Zitzer, B.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Compilation of papers presented by the VERITAS Collaboration at the 35th International Cosmic Ray Conference (ICRC), held July 12 through July 20, 2017 in Busan, South Korea., Comment: html page. 2017 ICRC, Busan, South Korea. A full list of author affiliations can be found at this link: https://veritas.sao.arizona.edu/conferences/ICRC2017_AuthList.html

Published
2017

17. Multiwavelength Observations of the Blazar VER J0521+211 during an Elevated TeV Gamma-Ray State

Author

Adams, C. B., primary, Batista, P., additional, Benbow, W., additional, Brill, A., additional, Brose, R., additional, Buckley, J. H., additional, Capasso, M., additional, Christiansen, J. L., additional, Errando, M., additional, Feng, Q., additional, Finley, J. P., additional, Foote, G. M., additional, Fortson, L., additional, Furniss, A., additional, Gallagher, G., additional, Gent, A., additional, Giuri, C., additional, Hanlon, W. F., additional, Hanna, D., additional, Hassan, T., additional, Hervet, O., additional, Holder, J., additional, Hona, B., additional, Hughes, G., additional, Humensky, T. B., additional, Jin, W., additional, Kaaret, P., additional, Kertzman, M., additional, Kieda, D., additional, Kleiner, T. K., additional, Krennrich, F., additional, Kumar, S., additional, Lang, M. J., additional, Lundy, M., additional, Maier, G., additional, Millis, J., additional, Moriarty, P., additional, Mukherjee, R., additional, Nievas-Rosillo, M., additional, O’Brien, S., additional, Ong, R. A., additional, Otte, A. N., additional, Patel, S., additional, Patel, S. R., additional, Pfrang, K., additional, Pohl, M., additional, Prado, R. R., additional, Pueschel, E., additional, Quinn, J., additional, Ragan, K., additional, Reynolds, P. T., additional, Ribeiro, D., additional, Roache, E., additional, Ryan, J. L., additional, Sadeh, I., additional, Santander, M., additional, Sembroski, G. H., additional, Shang, R., additional, Stevenson, B., additional, Tucci, J. V., additional, Vassiliev, V. V., additional, Wakely, S. P., additional, Weinstein, A., additional, Wells, R. M., additional, Williams, D. A., additional, Williamson, T. J., additional, Acciari, V. A., additional, Aniello, T., additional, Ansoldi, S., additional, Antonelli, L. A., additional, Engels, A. Arbet, additional, Arcaro, C., additional, Artero, M., additional, Asano, K., additional, Baack, D., additional, Babić, A., additional, Baquero, A., additional, de Almeida, U. Barres, additional, Barrio, J. A., additional, Batković, I., additional, González, J. Becerra, additional, Bednarek, W., additional, Bernardini, E., additional, Bernardos, M., additional, Berti, A., additional, Besenrieder, J., additional, Bhattacharyya, W., additional, Bigongiari, C., additional, Biland, A., additional, Blanch, O., additional, Bökenkamp, H., additional, Bonnoli, G., additional, Bošnjak, Ž., additional, Burelli, I., additional, Busetto, G., additional, Carosi, R., additional, Ceribella, G., additional, Cerruti, M., additional, Chai, Y., additional, Chilingarian, A., additional, Cikota, S., additional, Colombo, E., additional, Contreras, J. L., additional, Cortina, J., additional, Covino, S., additional, D’Amico, G., additional, D’Elia, V., additional, Vela, P. Da, additional, Dazzi, F., additional, Angelis, A. De, additional, Lotto, B. De, additional, Popolo, A. Del, additional, Delfino, M., additional, Delgado, J., additional, Mendez, C. Delgado, additional, Depaoli, D., additional, Pierro, F. Di, additional, Venere, L. Di, additional, Souto Espiñeira, E. Do, additional, Prester, D. Dominis, additional, Donini, A., additional, Dorner, D., additional, Doro, M., additional, Elsaesser, D., additional, Ramazani, V. Fallah, additional, Fariña, L., additional, Fattorini, A., additional, Font, L., additional, Fruck, C., additional, Fukami, S., additional, Fukazawa, Y., additional, López, R. J. García, additional, Garczarczyk, M., additional, Gasparyan, S., additional, Gaug, M., additional, Giglietto, N., additional, Giordano, F., additional, Gliwny, P., additional, Godinović, N., additional, Green, J. G., additional, Green, D., additional, Hadasch, D., additional, Hahn, A., additional, Heckmann, L., additional, Herrera, J., additional, Hrupec, D., additional, Hütten, M., additional, Inada, T., additional, Iotov, R., additional, Ishio, K., additional, Iwamura, Y., additional, Martínez, I. Jiménez, additional, Jormanainen, J., additional, Jouvin, L., additional, Kerszberg, D., additional, Kobayashi, Y., additional, Kubo, H., additional, Kushida, J., additional, Lamastra, A., additional, Lelas, D., additional, Leone, F., additional, Lindfors, E., additional, Linhoff, L., additional, Lombardi, S., additional, Longo, F., additional, López-Coto, R., additional, López-Moya, M., additional, López-Oramas, A., additional, Loporchio, S., additional, Lorini, A., additional, de Oliveira Fraga, B. Machado, additional, Maggio, C., additional, Majumdar, P., additional, Makariev, M., additional, Maneva, G., additional, Manganaro, M., additional, Mannheim, K., additional, Mariotti, M., additional, Martínez, M., additional, Aguilar, A. Mas, additional, Mazin, D., additional, Menchiari, S., additional, Mender, S., additional, Mićanović, S., additional, Miceli, D., additional, Miener, T., additional, Miranda, J. M., additional, Mirzoyan, R., additional, Molina, E., additional, Mondal, H. A., additional, Moralejo, A., additional, Morcuende, D., additional, Moreno, V., additional, Nakamori, T., additional, Nanci, C., additional, Nava, L., additional, Neustroev, V., additional, Rosillo, M. Nievas, additional, Nigro, C., additional, Nilsson, K., additional, Nishijima, K., additional, Noda, K., additional, Nozaki, S., additional, Ohtani, Y., additional, Oka, T., additional, Otero-Santos, J., additional, Paiano, S., additional, Palatiello, M., additional, Paneque, D., additional, Paoletti, R., additional, Paredes, J. M., additional, Pavletić, L., additional, Peñil, P., additional, Persic, M., additional, Pihet, M., additional, Moroni, P. G. Prada, additional, Prandini, E., additional, Priyadarshi, C., additional, Puljak, I., additional, Rhode, W., additional, Ribó, M., additional, Rico, J., additional, Righi, C., additional, Rugliancich, A., additional, Sahakyan, N., additional, Saito, T., additional, Sakurai, S., additional, Satalecka, K., additional, Saturni, F. G., additional, Schleicher, B., additional, Schmidt, K., additional, Schmuckermaier, F., additional, Schubert, J. L., additional, Schweizer, T., additional, Sitarek, J., additional, Šnidarić, I., additional, Sobczynska, D., additional, Spolon, A., additional, Stamerra, A., additional, Strišković, J., additional, Strom, D., additional, Strzys, M., additional, Suda, Y., additional, Surić, T., additional, Takahashi, M., additional, Takeishi, R., additional, Tavecchio, F., additional, Temnikov, P., additional, Terzić, T., additional, Teshima, M., additional, Tosti, L., additional, Truzzi, S., additional, Tutone, A., additional, Ubach, S., additional, Scherpenberg, J. van, additional, Vanzo, G., additional, Acosta, M. Vazquez, additional, Ventura, S., additional, Verguilov, V., additional, Viale, I., additional, Vigorito, C. F., additional, Vitale, V., additional, Vovk, I., additional, Will, M., additional, Wunderlich, C., additional, Yamamoto, T., additional, and Zarić, D., additional

Published
2022
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21. The Great Markarian 421 Flare of 2010 February: Multiwavelength Variability and Correlation Studies

Author

Abeysekara, A. U., Benbow, W., Bird, R., Brill, A., Brose, R., Buchovecky, M., Buckley, J. H., Christiansen, J. L., Chromey, A. J., Daniel, M. K., Dumm, J., Falcone, A., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Galante, N., Gent, A., Gillanders, G. H., Giuri, C., Gueta, O., Hassan, T., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Moriarty, P., Mukherjee, R., Nelson, T., Nieto, D., Nievas-Rosillo, M., O’Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pichel, A., Pohl, M., Prado, R. R., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rovero, A. C., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Stevenson, B., Sushch, I., Tyler, J., Vassiliev, V. V., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Zitzer, B., Acciari, V. A., Ansoldi, S., Antonelli, L. A., Arbet Engels, A., Baack, D., Babić, A., Banerjee, B., Barres de Almeida, U., Barrio, J. A., Becerra González, J., Bednarek, W., Bellizzi, L., Bernardini, E., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Biland, A., Blanch, O., Bonnoli, G., Busetto, G., Carosi, R., Ceribella, G., Chai, Y., Cikota, S., Colak, S. M., Colin, U., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D’Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Di Pierro, F., Do Souto Espiñera, E., Dominis Prester, D., Dorner, D., Doro, M., Einecke, S., Elsaesser, D., Fallah Ramazani, V., Fattorini, A., Fernández-Barral, A., Ferrara, G., Fidalgo, D., Foffano, L., Fonseca, M. V., Font, L., Fruck, C., Galindo, D., Gallozzi, S., García López, R. J., Garczarczyk, M., Gasparyan, S., Gaug, M., Godinović, N., Green, D., Guberman, D., Hadasch, D., Hahn, A., Herrera, J., Hoang, J., Hrupec, D., Inoue, S., Ishio, K., Iwamura, Y., Kubo, H., Kushida, J., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Lombardi, S., Longo, F., López, M., López-Coto, R., López-Oramas, A., Machado de Oliveira Fraga, B., Maggio, C., Majumdar, P., Makariev, M., Mallamaci, M., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Masuda, S., Mazin, D., Miceli, D., Minev, M., Miranda, J. M., Mirzoyan, R., Molina, E., Moralejo, A., Morcuende, D., Moreno, V., Moretti, E., Munar-Adrover, P., Neustroev, V., Niedzwiecki, A., Nievas Rosillo, M., Nigro, C., Nilsson, K., Ninci, D., Nishijima, K., Noda, K., Nogués, L., Nöthe, M., Paiano, S., Palacio, J., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Peñil, P., Peresano, M., Persic, M., Prada Moroni, P. G., Prandini, E., Puljak, I., Rhode, W., Ribó, M., Rico, J., Righi, C., Rugliancich, A., Saha, L., Sahakyan, N., Saito, T., Satalecka, K., Schweizer, T., Sitarek, J., Šnidarić, I., Sobczynska, D., Somero, A., Stamerra, A., Strom, D., Strzys, M., Sun, S., Surić, T., Tavecchio, F., Temnikov, P., Terzić, T., Teshima, M., Torres-Albà, N., Tsujimoto, S., van Scherpenberg, J., Vanzo, G., Vazquez Acosta, M., Vovk, I., Will, M., Zarić, D., Aller, H. D., Aller, M. F., Carini, M. T., Horan, D., Jordan, B., Jorstad, S. G., Kurtanidze, O. M., Kurtanidze, S. O., Lähteenmäki, A., Larionov, V. M., Larionova, E. G., Madejski, G., Marscher, A. P., Max-Moerbeck, W., Moody, J. Ward, Morozova, D. A., Nikolashvili, M. G., Raiteri, C. M., Readhead, A. C. S., Richards, J. L., Sadun, A. C., Sakamoto, T., Sigua, L. A., Smith, P. S., Talvikki, H., Tammi, J., Tornikoski, M., Troitsky, I. S., Villata, M., (VERITAS Collaboration), (MAGIC Collaboration), (Multiwavelength Partners), Department of Energy (US), Smithsonian Institution, National Science Foundation (US), National Energy Research Scientific Computing Center (US), German Research Foundation, Istituto Nazionale di Fisica Nucleare, Istituto Nazionale di Astrofisica, Ministerio de Economía y Competitividad (España), Department of Atomic Energy (India), Japan Society for the Promotion of Science, Ministry of Education, Culture, Sports, Science and Technology (Japan), Croatian Science Foundation, University of Rijeka, Polish National Agency for Academic Exchange, National Aeronautics and Space Administration (US), Shota Rustaveli National Science Foundation, Boston University, University of Utah, Harvard University, University of California Los Angeles, Columbia University, University of Potsdam, Washington University St. Louis, California Polytechnic State University, San Luis Obispo, Iowa State University, University of Minnesota Twin Cities, Pennsylvania State University, Purdue University, California State University, East Bay, Georgia Institute of Technology, National University of Ireland, Galway, German Electron Synchrotron, University of California Santa Cruz, University of Delaware, University of Iowa, DePauw University, McGill University, Complutense University, University College Dublin, University of Wisconsin-Madison, Universidad de Buenos Aires, Cork Institute of Technology, University of Alabama, University of Chicago, Instituto de Astrofísica de Canarias, University of Udine, INAF, Osservatorio Astronomico di Roma, Swiss Federal Institute of Technology Zurich, Dortmund University, Saha Institute of Nuclear Physics, Centro Brasileiro de Pesquisas Físicas, University of Łódź, University of Siena, National Institute for Nuclear Physics, Max Planck Institute for Physics, Institute for High Energy Physics, University of Padova, University of Pisa, University of Würzburg, University of Turku, Autonomous University of Barcelona, University of Barcelona, National Academy of Sciences of the Republic of Armenia, The University of Tokyo, Bulgarian Academy of Sciences, Fudan University, University of Michigan, Ann Arbor, Western Kentucky University, CNRS, Dublin Institute for Advanced Studies, Ilia State University, Department of Electronics and Nanoengineering, St. Petersburg State University, United States Department of Energy, Universidad de Chile, Brigham Young University, California Institute of Technology, University of Colorado Denver, Aoyama Gakuin University, University of Arizona, Metsähovi Radio Observatory, Aalto-yliopisto, Aalto University, Abeysekara, A. U., Benbow, W., Bird, R., Brill, A., Brose, R., Buchovecky, M., Buckley, J. H., Christiansen, J. L., Chromey, A. J., Daniel, M. K., Dumm, J., Falcone, A., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Galante, N., Gent, A., Gillanders, G. H., Giuri, C., Gueta, O., Hassan, T., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Moriarty, P., Mukherjee, R., Nelson, T., Nieto, D., Nievas-Rosillo, M., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pichel, A., Pohl, M., Prado, R. R., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rovero, A. C., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Stevenson, B., Sushch, I., Tyler, J., Vassiliev, V. V., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Zitzer, B., Acciari, V. A., Ansoldi, S., Antonelli, L. A., Arbet Engels, A., Baack, D., Babic, A., Banerjee, B., Barres De Almeida, U., Barrio, J. A., Becerra Gonzalez, J., Bednarek, W., Bellizzi, L., Bernardini, E., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Biland, A., Blanch, O., Bonnoli, G., Busetto, G., Carosi, R., Ceribella, G., Chai, Y., Cikota, S., Colak, S. M., Colin, U., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Di Pierro, F., Do Souto Espiñera, E., Dominis Prester, D., Dorner, D., Doro, M., Einecke, S., Elsaesser, D., Fallah Ramazani, V., Fattorini, A., Fernandez-Barral, A., Ferrara, G., Fidalgo, D., Foffano, L., Fonseca, M. V., Font, L., Fruck, C., Galindo, D., Gallozzi, S., Garcia Lopez, R. J., Garczarczyk, M., Gasparyan, S., Gaug, M., Godinovic, N., Green, D., Guberman, D., Hadasch, D., Hahn, A., Herrera, J., Hoang, J., Hrupec, D., Inoue, S., Ishio, K., Iwamura, Y., Kubo, H., Kushida, J., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Lombardi, S., Longo, F., Lopez, M., Lopez-Coto, R., Lopez-Oramas, A., Machado De Oliveira Fraga, B., Maggio, C., Majumdar, P., Makariev, M., Mallamaci, M., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Mariotti, M., Martinez, M., Masuda, S., Mazin, D., Miceli, D., Minev, M., Miranda, J. M., Mirzoyan, R., Molina, E., Moralejo, A., Morcuende, D., Moreno, V., Moretti, E., Munar-Adrover, P., Neustroev, V., Niedzwiecki, A., Nievas Rosillo, M., Nigro, C., Nilsson, K., Ninci, D., Nishijima, K., Noda, K., Nogues, L., Nothe, M., Paiano, S., Palacio, J., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Peñil, P., Peresano, M., Persic, M., Prada Moroni, P. G., Prandini, E., Puljak, I., Rhode, W., Ribo, M., Rico, J., Righi, C., Rugliancich, A., Saha, L., Sahakyan, N., Saito, T., Satalecka, K., Schweizer, T., Sitarek, J., Snidaric, I., Sobczynska, D., Somero, A., Stamerra, A., Strom, D., Strzys, M., Sun, S., Suric, T., Tavecchio, F., Temnikov, P., Terzic, T., Teshima, M., Torres-Alba, N., Tsujimoto, S., Van Scherpenberg, J., Vanzo, G., Vazquez Acosta, M., Vovk, I., Will, M., Zaric, D., Aller, H. D., Aller, M. F., Carini, M. T., Horan, D., Jordan, B., Jorstad, S. G., Kurtanidze, O. M., Kurtanidze, S. O., Lahteenmaki, A., Larionov, V. M., Larionova, E. G., Madejski, G., Marscher, A. P., Max-Moerbeck, W., Moody, J. W., Morozova, D. A., Nikolashvili, M. G., Raiteri, C. M., Readhead, A. C. S., Richards, J. L., Sadun, A. C., Sakamoto, T., Sigua, L. A., Smith, P. S., Talvikki, H., Tammi, J., Tornikoski, M., Troitsky, I. S., and Villata, M.

Subjects
Multiple days, Gamma-ray astronomY, 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, Flux, Markarian galaxies, Astrophysics, Blazar, 01 natural sciences, 7. Clean energy, BL Lacertae object, High energy astrophysic, law.invention, law, Observatory, BL Lacertae objects, Blazars, High energy astrophysics, Relativistic jets, Gamma-ray astronomy, Time domain astronomy, Relativistic jet, 0103 physical sciences, MAGIC (telescope), BL lacertae objects, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, Astronomy and Astrophysics, Light curve, Space and Planetary Science, Markarian galaxie, Electrónica, Electricidad, Flare
Abstract

We report on variability and correlation studies using multiwavelength observations of the blazar Mrk 421 during the month of 2010 February, when an extraordinary flare reaching a level of ∼27 Crab Units above 1 TeV was measured in very high energy (VHE) γ-rays with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) observatory. This is the highest flux state for Mrk 421 ever observed in VHE γ-rays. Data are analyzed from a coordinated campaign across multiple instruments, including VHE γ-ray (VERITAS, Major Atmospheric Gamma-ray Imaging Cherenkov), high-energy γ-ray (Fermi-LAT), X-ray (Swift, Rossi X-ray Timing Experiment, MAXI), optical (including the GASP-WEBT collaboration and polarization data), and radio (Metsahovi, Owens Valley Radio Observatory, University of Michigan Radio Astronomy Observatory). Light curves are produced spanning multiple days before and after the peak of the VHE flare, including over several flare "decline" epochs. The main flare statistics allow 2 minute time bins to be constructed in both the VHE and optical bands enabling a cross-correlation analysis that shows evidence for an optical lag of ∼25-55 minutes, the first time-lagged correlation between these bands reported on such short timescales. Limits on the Doppler factor (δ ⪆ 33) and the size of the emission region (δR≲ 3.8 × 10cm) are obtained from the fast variability observed by VERITAS during the main flare. Analysis of 10 minute binned VHE and X-ray data over the decline epochs shows an extraordinary range of behavior in the flux-flux relationship, from linear to quadratic to lack of correlation to anticorrelation. Taken together, these detailed observations of an unprecedented flare seen in Mrk 421 are difficult to explain with the classic single-zone synchrotron self-Compton model., This research is supported by grants from the U.S. Department of Energy Office of Science, the U.S. National Science Foundation, the Smithsonian Institution, and NSERC in Canada. This research used resources provided by the Open Science Grid, which is supported by the National Science Foundation and the U.S. Department of Energy’s Office of Science, and the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility operated under contract No. DE-AC02- 05CH11231. We acknowledge the excellent work of the technical support staff at the Fred Lawrence Whipple Observatory and the collaborating institutions in the construction and operation of the instrument. The MAGIC collaboration would like to thank the Instituto de Astrofísica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The financial support of the German BMBF and MPG, the Italian INFN and INAF, the Swiss National Fund SNF, the ERDF under the Spanish MINECO (FPA2015-69818-P, FPA2012-36668, FPA2015-68378-P, FPA2015-69210-C6-2- R, FPA2015-69210-C6-4-R, FPA2015-69210-C6-6-R, AYA2015-71042-P, AYA2016-76012-C3-1-P, ESP2015- 71662-C2-2-P, FPA201790566REDC), the Indian Department of Atomic Energy, the Japanese JSPS and MEXT, and the Bulgarian Ministry of Education and Science, National RI Roadmap Project DO1-153/28.08.2018 is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia “Severo Ochoa” SEV-2016-0588 and SEV2015-0548 and Unidad de Excelencia “María de Maeztu” MDM-2014-0369, the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782, the University of Rijeka Project 13.12.1.3.02, the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, the Polish National Research Centre grant UMO-2016/22/M/ST9/00382, and the Brazilian MCTIC, CNPq, and FAPERJ. This publication makes use of data obtained at Metsähovi Radio Observatory, operated by Aalto University, Finland, and the OVRO 40 m monitoring program, which is supported in part by NASA grants NNX08AW31G, NNX11A043G, and NNX14AQ89G and NSF grants AST-0808050 and AST1109911. The UMRAO data were obtained through NSF grant AST 0607523 and NASA Fermi GI award NNX09AU16G. The St. Petersburg University team acknowledges support from Russian RFBR foundation, grant 12-02-00452. The Abastumani Observatory team acknowledges financial support by the Shota Rustaveli National Science Foundation through project FR/577/6-320/13. The Steward Observatory data were obtained under Fermi Guest Investigator Program grant NNX09AU10G. The research at Boston University is supported by NASA grant 80NSSC17K0649 and NSF grant AST-1615796. Software. VEGAS (Cogan 2008), Event Display (Daniel 2008), MARS (Moralejo et al. 2009), Fermi Science Tools81, HEASoft (FTOOLS+XANADU; HEASARC 2014), REX,85 Xspec (Arnaud 1996), emcee (Foreman-Mackey et al. 2013).

Published
2020

24. The Great Markarian 421 flare of 2010 February:multiwavelength variability and correlation studies

Author

Abeysekara, A. U. (A. U.), Benbow, W. (W.), Bird, R. (R.), Brill, A. (A.), Brose, R. (R.), Buchovecky, M. (M.), Buckley, J. H. (J. H.), Christiansen, J. L. (J. L.), Chromey, A. J. (A. J.), Daniel, M. K. (M. K.), Dumm, J. (J.), Falcone, A. (A.), Feng, Q. (Q.), Finley, J. P. (J. P.), Fortson, L. (L.), Furniss, A. (A.), Galante, N. (N.), Gent, A. (A.), Gillanders, G. H. (G. H.), Giuri, C. (C.), Gueta, O. (O.), Hassan, T. (T.), Hervet, O. (O.), Holder, J. (J.), Hughes, G. (G.), Humensky, T. B. (T. B.), Johnson, C. A. (C. A.), Kaaret, P. (P.), Kar, P. (P.), Kelley-Hoskins, N. (N.), Kertzman, M. (M.), Kieda, D. (D.), Krause, M. (M.), Krennrich, F. (F.), Kumar, S. (S.), Lang, M. J. (M. J.), Moriarty, P. (P.), Mukherjee, R. (R.), Nelson, T. (T.), Nieto, D. (D.), Nievas-Rosillo, M. (M.), O'Brien, S. (S.), Ong, R. A. (R. A.), Otte, A. N. (A. N.), Park, N. (N.), Petrashyk, A. (A.), Pichel, A. (A.), Pohl, M. (M.), Prado, R. R. (R. R.), Pueschel, E. (E.), Quinn, J. (J.), Ragan, K. (K.), Reynolds, P. T. (P. T.), Richards, G. T. (G. T.), Roache, E. (E.), Rovero, A. C. (A. C.), Rulten, C. (C.), Sadeh, I. (I), Santander, M. (M.), Sembroski, G. H. (G. H.), Shahinyan, K. (K.), Stevenson, B. (B.), Sushch, I. (I), Tyler, J. (J.), Vassiliev, V. V. (V. V.), Wakely, S. P. (S. P.), Weinstein, A. (A.), Wells, R. M. (R. M.), Wilcox, P. (P.), Wilhelm, A. (A.), Williams, D. A. (D. A.), Zitzer, B. (B.), Acciari, V. A. (V. A.), Ansoldi, S. (S.), Antonelli, L. A. (L. A.), Engels, A. A. (A. Arbet), Baack, D. (D.), Babic, A. (A.), Banerjee, B. (B.), Barres de Almeida, U. (U.), Barrio, J. A. (J. A.), Becerra Gonzalez, J. (J.), Bednarek, W. (W.), Bellizzi, L. (L.), Bernardini, E. (E.), Berti, A. (A.), Besenrieder, J. (J.), Bhattacharyya, W. (W.), Bigongiari, C. (C.), Biland, A. (A.), Blanch, O. (O.), Bonnoli, G. (G.), Busetto, G. (G.), Carosi, R. (R.), Ceribella, G. (G.), Chai, Y. (Y.), Cikota, S. (S.), Colak, S. M. (S. M.), Colin, U. (U.), Colombo, E. (E.), Contreras, J. L. (J. L.), Cortina, J. (J.), Covino, S. (S.), D'Elia, V. (V), Vela, P. (P.), Dazzi, F. (F.), De Angelis, A. (A.), De Lotto, B. (B.), Delfino, M. (M.), Delgado, J. (J.), Di Pierro, F. (F.), Souto Espinera, E. (E.), Prester, D. D. (D. Dominis), Dorner, D. (D.), Doro, M. (M.), Einecke, S. (S.), Elsaesser, D. (D.), Ramazani, V. F. (V. Fallah), Fattorini, A. (A.), Fernandez-Barral, A. (A.), Ferrara, G. (G.), Fidalgo, D. (D.), Foffano, L. (L.), Fonseca, M. V. (M., V), Font, L. (L.), Fruck, C. (C.), Galindo, D. (D.), Gallozzi, S. (S.), Garcia Lopez, R. J. (R. J.), Garczarczyk, M. (M.), Gasparyan, S. (S.), Gaug, M. (M.), Godinovic, N. (N.), Green, D. (D.), Guberman, D. (D.), Hadasch, D. (D.), Hahn, A. (A.), Herrera, J. (J.), Hoang, J. (J.), Hrupec, D. (D.), Inoue, S. (S.), Ishio, K. (K.), Iwamura, Y. (Y.), Kubo, H. (H.), Kushida, J. (J.), Lamastra, A. (A.), Lelas, D. (D.), Leone, F. (F.), Lindfors, E. (E.), Lombardi, S. (S.), Longo, F. (F.), Lopez, M. (M.), Lopez-Coto, R. (R.), Lopez-Oramas, A. (A.), Machado de Oliveira Fraga, B. (B.), Maggio, C. (C.), Majumdar, P. (P.), Makariev, M. (M.), Mallamaci, M. (M.), Maneva, G. (G.), Manganaro, M. (M.), Mannheim, K. (K.), Maraschi, L. (L.), Mariotti, M. (M.), Martinez, M. (M.), Masuda, S. (S.), Mazin, D. (D.), Miceli, D. (D.), Minev, M. (M.), Miranda, J. M. (J. M.), Mirzoyan, R. (R.), Molina, E. (E.), Moralejo, A. (A.), Morcuende, D. (D.), Moreno, V. (V), Moretti, E. (E.), Munar-Adrover, P. (P.), Neustroev, V. (V), Niedzwiecki, A. (A.), Nievas Rosillo, M. (M.), Nigro, C. (C.), Nilsson, K. (K.), Ninci, D. (D.), Nishijima, K. (K.), Noda, K. (K.), Nogues, L. (L.), Noethe, M. (M.), Paiano, S. (S.), Palacio, J. (J.), Palatiello, M. (M.), Paneque, D. (D.), Paoletti, R. (R.), Paredes, J. M. (J. M.), Penil, P. (P.), Peresano, M. (M.), Persic, M. (M.), Moroni, P. G. (P. G. Prada), Prandini, E. (E.), Puljak, I. (I), Rhode, W. (W.), Ribo, M. (M.), Rico, J. (J.), Righi, C. (C.), Rugliancich, A. (A.), Saha, L. (L.), Sahakyan, N. (N.), Saito, T. (T.), Satalecka, K. (K.), Schweizer, T. (T.), Sitarek, J. (J.), Snidaric, I. (I), Sobczynska, D. (D.), Somero, A. (A.), Stamerra, A. (A.), Strom, D. (D.), Strzys, M. (M.), Sun, S. (S.), Suric, T. (T.), Tavecchio, F. (F.), Temnikov, P. (P.), Terzic, T. (T.), Teshima, M. (M.), Torres-Alba, N. (N.), Tsujimoto, S. (S.), van Scherpenberg, J. (J.), Vanzo, G. (G.), Vazquez Acosta, M. (M.), Vovk, I. (I), Will, M. (M.), Zaric, D. (D.), Aller, H. D. (H. D.), Aller, M. F. (M. F.), Carini, M. T. (M. T.), Horan, D. (D.), Jordan, B. (B.), Jorstad, S. G. (S. G.), Kurtanidze, O. M. (O. M.), Kurtanidze, S. O. (S. O.), Lahteenmaki, A. (A.), Larionov, V. M. (V. M.), Larionova, E. G. (E. G.), Madejski, G. (G.), Marscher, A. P. (A. P.), Max-Moerbeck, W. (W.), Moody, J. W. (J. Ward), Morozova, D. A. (D. A.), Nikolashvili, M. G. (M. G.), Raiteri, C. M. (C. M.), Readhead, A. C. (A. C. S.), Richards, J. L. (J. L.), Sadun, A. C. (A. C.), Sakamoto, T. (T.), Sigua, L. A. (L. A.), Smith, P. S. (P. S.), Talvikki, H. (H.), Tammi, J. (J.), Tornikoski, M. (M.), Troitsky, I. S. (I. S.), and Villata, M. (M.)

Subjects
Gamma-ray astronomy, Astrophysics::High Energy Astrophysical Phenomena, Time domain astronomy, BL Lacertae objects, Markarian galaxies, Relativistic jets, High energy astrophysics, Blazars
Abstract

We report on variability and correlation studies using multiwavelength observations of the blazar Mrk 421 during the month of 2010 February, when an extraordinary flare reaching a level of ~27 Crab Units above 1 TeV was measured in very high energy (VHE) γ-rays with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) observatory. This is the highest flux state for Mrk 421 ever observed in VHE γ-rays. Data are analyzed from a coordinated campaign across multiple instruments, including VHE γ-ray (VERITAS, Major Atmospheric Gamma-ray Imaging Cherenkov), high-energy γ-ray (Fermi-LAT), X-ray (Swift, Rossi X-ray Timing Experiment, MAXI), optical (including the GASP-WEBT collaboration and polarization data), and radio (Metsähovi, Owens Valley Radio Observatory, University of Michigan Radio Astronomy Observatory). Light curves are produced spanning multiple days before and after the peak of the VHE flare, including over several flare “decline“ epochs. The main flare statistics allow 2 minute time bins to be constructed in both the VHE and optical bands enabling a cross-correlation analysis that shows evidence for an optical lag of ~25–55 minutes, the first time-lagged correlation between these bands reported on such short timescales. Limits on the Doppler factor (δ ≳ 33) and the size of the emission region (δ⁻¹ RB ≲ × 10¹³ cm) are obtained from the fast variability observed by VERITAS during the main flare. Analysis of 10 minute binned VHE and X-ray data over the decline epochs shows an extraordinary range of behavior in the flux–flux relationship, from linear to quadratic to lack of correlation to anticorrelation. Taken together, these detailed observations of an unprecedented flare seen in Mrk 421 are difficult to explain with the classic single-zone synchrotron self-Compton model.

Published
2020

27. VERITAS and Fermi-LAT Observations of TeV Gamma-Ray Sources Discovered by HAWC in the 2HWC Catalog

Author

Abeysekara, A. U., Archer, A., Benbow, W., Bird, R., Brose, R., Buchovecky, M., Buckley, J. H., Bugaev, V., Chromey, A. J., Connolly, M. P., Cui, W., Michael Daniel, Falcone, A., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Hütten, M., Hanna, D., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Lin, T. T. Y., Mcarthur, S., Moriarty, P., Mukherjee, R., O’brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pohl, M., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Sushch, I., Tyler, J., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Williamson, T. J., Zitzer, B., Veritas, The Collaboration, Abdollahi, S., Ajello, M., Baldini, L., Barbiellini, G., Bastieri, D., Bellazzini, R., Berenji, B., Bissaldi, E., Blandford, R. D., Bonino, R., Bottacini, E., Brandt, T. J., Bruel, P., Buehler, R., Cameron, R. A., Caputo, R., Caraveo, P. A., Castro, D., Cavazzuti, E., Charles, E., Chiaro, G., Ciprini, S., Cohen-Tanugi, J., Costantin, D., Cutini, S., D’ammando, F., Palma, F., Di Lalla, N., Di Mauro, M., Di Venere, L., Domínguez, A., Favuzzi, C., Fegan, S. J., Franckowiak, A., Fukazawa, Y., Funk, S., Fusco, P., Gargano, F., Gasparrini, D., Giglietto, N., Giordano, F., Giroletti, M., Green, D., Grenier, I. A., Guillemot, L., Guiriec, S., Hays, E., Hewitt, J. W., Horan, D., Jóhannesson, G., Kensei, S., Kuss, M., Larsson, S., Latronico, L., Lemoine-Goumard, M., Li, J., Longo, F., Loparco, F., Lovellette, M. N., Lubrano, P., Magill, J. D., Maldera, S., Mazziotta, M. N., Mcenery, J. E., Michelson, P. F., Mitthumsiri, W., Mizuno, T., Monzani, M. E., Morselli, A., Moskalenko, I. V., Negro, M., Nuss, E., Ojha, R., Omodei, N., Orienti, M., Orlando, E., Palatiello, M., Paliya, V. S., Paneque, D., Perkins, J. S., Persic, M., Pesce-Rollins, M., Petrosian, V., Piron, F., Porter, T. A., Principe, G., Rainò, S., Rando, R., Rani, B., Razzano, M., Razzaque, S., Reimer, A., Reimer, O., Reposeur, T., Sgrò, C., Siskind, E. J., Spandre, G., Spinelli, P., Suson, D. J., Tajima, H., Thayer, J. B., Thompson, D. J., Torres, D. F., Tosti, G., Troja, E., Valverde, J., Vianello, G., Vogel, M., Wood, K., Yassine, M., The Fermi-LAT Collaboration, Alfaro, R., Álvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Avila Rojas, D., Ayala Solares, H. A., Becerril, A., Belmont-Moreno, E., Benzvi, S. Y., Bernal, A., Braun, J., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Castillo, M., Cotti, U., Cotzomi, J., Coutiño León, S., León, C., La Fuente, E., Dichiara, S., Dingus, B. L., Duvernois, M. A., Díaz-Vélez, J. C., Engel, K., Enriquez-Rivera, O., Fiorino, D. W., Fleischhack, H., Fraija, N., García-González, J. A., Garfias, F., González Muñoz, A., González, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hernandez-Almada, A., Hona, B., Hueyotl-Zahuantitla, F., Hui, C. M., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., León Vargas, H., Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Luna-García, R., López-Coto, R., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Martínez-Huerta, H., Matthews, J. A., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pelayo, R., Pretz, J., Pérez-Pérez, E. G., Ren, Z., Rho, C. D., Rivière, C., Rosa-González, D., Rosenberg, M., Ruiz-Velasco, E., Salazar, H., Salesa Greus, F., Sandoval, A., Schneider, M., Seglar Arroyo, M., Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Taboada, I., Tibolla, O., Tollefson, K., Torres, I., Ukwatta, T. N., Villaseñor, L., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yapici, T., Yodh, G., Zepeda, A., Zhou, H., Hawc, The Collaboration, Laboratoire Leprince-Ringuet (LLR), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Particules de Montpellier (LUPM), Université de Montpellier (UM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), VERITAS, Fermi-LAT, HAWC, Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Abeysekara, A. U., Archer, A., Benbow, W., Bird, R., Brose, R., Buchovecky, M., Buckley, J. H., Bugaev, V., Chromey, A. J., Connolly, M. P., Cui, W., Daniel, M. K., Falcone, A., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Hutten, M., Hanna, D., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Lin, T. T. Y., Mcarthur, S., Moriarty, P., Mukherjee, R., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pohl, M., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Sushch, I., Tyler, J., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Williamson, T. J., Zitzer, B., Abdollahi, S., Ajello, M., Baldini, L., Barbiellini, G., Bastieri, D., Bellazzini, R., Berenji, B., Bissaldi, E., Blandford, R. D., Bonino, R., Bottacini, E., Brandt, T. J., Bruel, P., Buehler, R., Cameron, R. A., Caputo, R., Caraveo, P. A., Castro, D., Cavazzuti, E., Charles, E., Chiaro, G., Ciprini, S., Cohen-Tanugi, J., Costantin, D., Cutini, S., D'Ammando, F., DE PALMA, Francesco, Lalla, N. D., Mauro, M. D., Venere, L. D., Dominguez, A., Favuzzi, C., Fegan, S. J., Franckowiak, A., Fukazawa, Y., Funk, S., Fusco, P., Gargano, F., Gasparrini, D., Giglietto, N., Giordano, F., Giroletti, M., Green, D., Grenier, I. A., Guillemot, L., Guiriec, S., Hays, E., Hewitt, J. W., Horan, D., Johannesson, G., Kensei, S., Kuss, M., Larsson, S., Latronico, L., Lemoine-Goumard, M., Li, J., Longo, F., Loparco, F., Lovellette, M. N., Lubrano, P., Magill, J. D., Maldera, S., Mazziotta, M. N., Mcenery, J. E., Michelson, P. F., Mitthumsiri, W., Mizuno, T., Monzani, M. E., Morselli, A., Moskalenko, I. V., Negro, M., Nuss, E., Ojha, R., Omodei, N., Orienti, M., Orlando, E., Palatiello, M., Paliya, V. S., Paneque, D., Perkins, J. S., Persic, M., Pesce-Rollins, M., Petrosian, V., Piron, F., Porter, T. A., Principe, G., Raino, S., Rando, R., Rani, B., Razzano, M., Razzaque, S., Reimer, A., Reimer, O., Reposeur, T., Sgro, C., Siskind, E. J., Spandre, G., Spinelli, P., Suson, D. J., Tajima, H., Thayer, J. B., Thompson, D. J., Torres, D. F., Tosti, G., Troja, E., Valverde, J., Vianello, G., Vogel, M., Wood, K., Yassine, M., Alfaro, R., Alvarez, C., Alvarez, J. D., Arceo, R., Arteaga-Velazquez, J. C., Rojas, D. A., Solares, H. A. A., Becerril, A., Belmont-Moreno, E., Benzvi, S. Y., Bernal, A., Braun, J., Brisbois, C., Caballero-Mora, K. S., Capistran, T., Carraminana, A., Casanova, S., Castillo, M., Cotti, U., Cotzomi, J., De Leon, S. C., Leon, C. D., Fuente, E. D. L., Dichiara, S., Dingus, B. L., Duvernois, M. A., Diaz-Velez, J. C., Engel, K., Enriquez-Rivera, O., Fiorino, D. W., Fleischhack, H., Fraija, N., Garcia-Gonzalez, J. A., Garfias, F., Munoz, A. G., Gonzalez, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hernandez-Almada, A., Hona, B., Hueyotl-Zahuantitla, F., Hui, C. M., Huntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. L., Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Luna-Garcia, R., Lopez-Coto, R., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martinez-Castro, J., Martinez-Huerta, H., Matthews, J. A., Miranda-Romagnoli, P., Moreno, E., Mostafa, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pelayo, R., Pretz, J., Perez-Perez, E. G., Ren, Z., Rho, C. D., Riviere, C., Rosa-Gonzalez, D., Rosenberg, M., Ruiz-Velasco, E., Salazar, H., Greus, F. S., Sandoval, A., Schneider, M., Arroyo, M. S., Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Taboada, I., Tibolla, O., Tollefson, K., Torres, I., Ukwatta, T. N., Villasenor, L., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yapici, T., Yodh, G., Zepeda, A., Zhou, H., ITA, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Hütten, M., Palma, F. De, Lalla, N. Di, Mauro, M. Di, Venere, L. Di, Jóhannesson, G., Arteaga-Velázquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Capistrán, T., De León, S. Coutino, León, C. De, Fuente, E. De La, Diaz-Vélez, J. C., Garcia-González, J. A., Munoz, A. González, González, M. M., Hüntemeyer, P., Vargas, H. León, López-Coto, R., Mostafá, M., Pérez-Pérez, E. G., Rosa-González, D., Greus, F. Salesa, and Arroyo, M. Seglar

Subjects
Physics, High energy, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Institut für Physik und Astronomie, Astronomy and Astrophysics, Astrophysics, gamma rays: general, Astronomy and Astrophysic, 01 natural sciences, Pulsar wind nebula, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], 0103 physical sciences, ddc:520, ddc:530, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, general [gamma rays], Cherenkov radiation, Fermi Gamma-ray Space Telescope
Abstract

International audience; The High Altitude Water Cherenkov (HAWC) collaboration recently published their 2HWC catalog, listing 39 very high energy (VHE; >100 GeV) gamma-ray sources based on 507 days of observation. Among these, 19 sources are not associated with previously known teraelectronvolt (TeV) gamma-ray sources. We have studied 14 of these sources without known counterparts with VERITAS and Fermi-LAT. VERITAS detected weak gamma-ray emission in the 1 TeV–30 TeV band in the region of DA 495, a pulsar wind nebula coinciding with 2HWC J1953+294, confirming the discovery of the source by HAWC. We did not find any counterpart for the selected 14 new HAWC sources from our analysis of Fermi-LAT data for energies higher than 10 GeV. During the search, we detected gigaelectronvolt (GeV) gamma-ray emission coincident with a known TeV pulsar wind nebula, SNR G54.1+0.3 (VER J1930+188), and a 2HWC source, 2HWC J1930+188. The fluxes for isolated, steady sources in the 2HWC catalog are generally in good agreement with those measured by imaging atmospheric Cherenkov telescopes. However, the VERITAS fluxes for SNR G54.1+0.3, DA 495, and TeV J2032+4130 are lower than those measured by HAWC, and several new HAWC sources are not detected by VERITAS. This is likely due to a change in spectral shape, source extension, or the influence of diffuse emission in the source region.

Published
2018

29. Multiwavelength Observations of the Blazar BL Lacertae

Author

Abeysekara, A. U., Benbow, W., Bird, R., Brantseg, T., Brose, R., Buchovecky, M., Buckley, J. H., Bugaev, V., Connolly, M. P., Cui, W., Daniel, M. K., Falcone, A., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Gillanders, G. H., Gunawardhana, I., Hütten, M., Hanna, D., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kertzman, M., Krennrich, F., Lang, M. J., Lin, T. T.Y., McArthur, S., Moriarty, P., Mukherjee, R., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pohl, Martin, Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Williams, D. A., Zitzer, B., Jorstad, S. G., Marscher, A. P., Lister, M. L., Kovalev, Y. Y., Pushkarev, A. B., Savolainen, T., Agudo, I., Molina, S. N., Gómez, J. L., Larionov, V. M., Borman, G. A., Mokrushina, A. A., Tornikoski, M., Lahteenmaki, A., Chamani, Wara, Enestam, S., Kiehlmann, S., Hovatta, T., Smith, P. S., Pontrelli, P., University of Utah, Harvard University, University of California Los Angeles, Iowa State University, University of Potsdam, Washington University St. Louis, National University of Ireland, Galway, Purdue University, Pennsylvania State University, McGill University, University of Minnesota Twin Cities, California State University, East Bay, German Electron Synchrotron, University of California Santa Cruz, University of Delaware, Columbia University, University of Iowa, DePauw University, University College Dublin, Georgia Institute of Technology, University of Chicago, Cork Institute of Technology, Boston University, RAS - P.N. Lebedev Physics Institute, Metsähovi Radio Observatory, CSIC, St. Petersburg State University, Crimean Astrophysical Observatory, Department of Electronics and Nanoengineering, California Institute of Technology, University of Turku, University of Arizona, Aalto-yliopisto, and Aalto University

Subjects
Astrophysics::High Energy Astrophysical Phenomena, active [galaxies], Astrophysics::Cosmology and Extragalactic Astrophysics, individual (BL Lacertae = VER J2202+422) [BL Lacertae objects]
Abstract

Combined with measurements made by very-long-baseline interferometry, the observations of fast TeV gamma-ray flares probe the structure and emission mechanism of blazar jets. However, only a handful of such flares have been detected to date, and only within the last few years have these flares been observed from lower-frequency-peaked BL Lac objects and flat-spectrum radio quasars. We report on a fast TeV gamma-ray flare from the blazar BL Lacertae observed by the Very Energetic Radiation Imaging Telescope Array System (VERITAS). with a rise time of ∼2.3 hr and a decay time of ∼36 min. The peak flux above 200 GeV is (4.2 ± 0.6) ×10-6 photon m-2 s-1 measured with a 4-minute-binned light curve, corresponding to ∼180% of the flux that is observed from the Crab Nebula above the same energy threshold. Variability contemporaneous with the TeV gamma-ray flare was observed in GeV gamma-ray, X-ray, and optical flux, as well as in optical and radio polarization. Additionally, a possible moving emission feature with superluminal apparent velocity was identified in Very Long Baseline Array observations at 43 GHz, potentially passing the radio core of the jet around the time of the gamma-ray flare. We discuss the constraints on the size, Lorentz factor, and location of the emitting region of the flare, and the interpretations with several theoretical models that invoke relativistic plasma passing stationary shocks.

Published
2018

30. A Very High Energy γ -Ray Survey toward the Cygnus Region of the Galaxy

Author

Abeysekara, A. U., Archer, A., Aune, T., Benbow, W., Bird, R., Brose, R., Buchovecky, M., Bugaev, V., Cui, W., Daniel, M. K., Falcone, A., Feng, Q., Finley, J. P., Fleischhack, H., Flinders, A., Fortson, L., Furniss, A., Gotthelf, E. V., Grube, J., Hanna, D., Hervet, O., Holder, J., Huang, K., Hughes, G., Humensky, T. B., Huetten, Moritz, Johnson, C. A., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krause, M., Kumar, S., Lang, M. J., Lin, T. T. Y., Maier, Gernot, McArthur, S., Moriarty, P., Mukherjee, R., O’Brien, S., Ong, R. A., Otte, A. N., Pandel, D., Park, N., Petrashyk, A., Pohl, M., Popkow, A., Pueschel, Elisa, Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rousselle, J., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Tyler, J., Vassiliev, V. V., Wakely, S. P., Ward, J. E., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, Alina, Williams, D. A., and Zitzer, B.

Abstract

The astrophysical journal / 1 861(2), 134 (2018). doi:10.3847/1538-4357/aac4a2, We present results from deep observations toward the Cygnus region using 300 hr of very high energy (VHE) γ-ray data taken with the VERITAS Cerenkov telescope array and over 7 yr of high-energy γ-ray data taken with the Fermi satellite at an energy above 1 GeV. As the brightest region of diffuse γ-ray emission in the northern sky, the Cygnus region provides a promising area to probe the origins of cosmic rays. We report the identification of a potential Fermi-LAT counterpart to VER J2031+415 (TeV J2032+4130) and resolve the extended VHE source VER J2019+368 into two source candidates (VER J2018+367* and VER J2020+368*) and characterize their energy spectra. The Fermi-LAT morphology of 3FGL J2021.0+4031e (the Gamma Cygni supernova remnant) was examined, and a region of enhanced emission coincident with VER J2019+407 was identified and jointly fit with the VERITAS data. By modeling 3FGL J2015.6+3709 as two sources, one located at the location of the pulsar wind nebula CTB 87 and one at the quasar QSO J2015+371, a continuous spectrum from 1 GeV to 10 TeV was extracted for VER J2016+371 (CTB 87). An additional 71 locations coincident with Fermi-LAT sources and other potential objects of interest were tested for VHE γ-ray emission, with no emission detected and upper limits on the differential flux placed at an average of 2.3% of the Crab Nebula flux. We interpret these observations in a multiwavelength context and present the most detailed γ-ray view of the region to date., Published by Univ.11032, Chicago, Ill. [u.a.]

Published
2018
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31. HESS J1943+213: An Extreme Blazar Shining through the Galactic Plane

Author

Archer, A., Benbow, W., Bird, R., Brose, R., Buchovecky, M., Bugaev, V., Cui, W., Daniel, M. K., Falcone, A., Feng, Q., Finley, J. P., Flinders, A., Fortson, L., Furniss, A., Gillanders, G. H., Hütten, M., Hanna, D., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Lin, T. T. Y., McArthur, S., Moriarty, P., Mukherjee, R., Nieto, D., O’Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pohl, M., Popkow, A., Pueschel, Elisa, Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rulten, C., Sadeh, I., Sembroski, G. H., Shahinyan, K., Tyler, J., Wakely, S. P., Weiner, O. M., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Brisken, W. F., and Pontrelli, P.

Abstract

The astrophysical journal / 1 862(1), 41 (2018). doi:10.3847/1538-4357/aacbd0, HESS J1943+213 is a very high energy (VHE; >100 GeV) γ-ray source in the direction of the Galactic plane. Studies exploring the classification of the source are converging toward its identification as an extreme synchrotron BL Lac object. Here we present 38 hr of VERITAS observations of HESS J1943+213 taken over 2 yr. The source is detected with a significance of ~20 standard deviations, showing a remarkably stable flux and spectrum in VHE γ-rays. Multifrequency Very Long Baseline Array (VLBA) observations of the source confirm the extended, jet-like structure previously found in the 1.6 GHz band with the European VLBI Network and detect this component in the 4.6 and 7.3 GHz bands. The radio spectral indices of the core and the jet and the level of polarization derived from the VLBA observations are in a range typical for blazars. Data from VERITAS, Fermi-LAT, Swift-XRT, the FLWO 48'' telescope, and archival infrared and hard X-ray observations are used to construct and model the spectral energy distribution (SED) of the source with a synchrotron self-Compton model. The well-measured γ-ray peak of the SED with VERITAS and Fermi-LAT provides constraining upper limits on the source redshift. Possible contribution of secondary γ-rays from ultra-high-energy cosmic-ray-initiated electromagnetic cascades to the γ-ray emission is explored, finding that only a segment of the VHE spectrum can be accommodated with this process. A variability search is performed across X-ray and γ-ray bands. No statistically significant flux or spectral variability is detected., Published by Univ.11032, Chicago, Ill. [u.a.]

Published
2018
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32. Measurement of the Extragalactic Background Light Spectral Energy Distribution with VERITAS

Author

Abeysekara, A. U., primary, Archer, A., additional, Benbow, W., additional, Bird, R., additional, Brill, A., additional, Brose, R., additional, Buchovecky, M., additional, Calderon-Madera, D., additional, Christiansen, J. L., additional, Cui, W., additional, Daniel, M. K., additional, Falcone, A., additional, Feng, Q., additional, Fernandez-Alonso, M., additional, Finley, J. P., additional, Fortson, L., additional, Furniss, A., additional, Gent, A., additional, Giuri, C., additional, Gueta, O., additional, Hanna, D., additional, Hassan, T., additional, Hervet, O., additional, Holder, J., additional, Hughes, G., additional, Humensky, T. B., additional, Johnson, C. A., additional, Kaaret, P., additional, Kertzman, M., additional, Kieda, D., additional, Krause, M., additional, Krennrich, F., additional, Kumar, S., additional, Lang, M. J., additional, Maier, G., additional, Moriarty, P., additional, Mukherjee, R., additional, Nievas-Rosillo, M., additional, O’Brien, S., additional, Ong, R. A., additional, Pfrang, K., additional, Pohl, M., additional, Prado, R. R., additional, Pueschel, E., additional, Quinn, J., additional, Ragan, K., additional, Reynolds, P. T., additional, Ribeiro, D., additional, Richards, G. T., additional, Roache, E., additional, Rovero, A. C., additional, Sadeh, I., additional, Santander, M., additional, Sembroski, G. H., additional, Shahinyan, K., additional, Sushch, I., additional, Svraka, T., additional, Weinstein, A., additional, Wells, R. M., additional, Wilcox, P., additional, Wilhelm, A., additional, Williams, D. A., additional, Williamson, T. J, additional, and Zitzer, B., additional

Published
2019
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33. A Search for Pulsed Very High-energy Gamma-Rays from 13 Young Pulsars in Archival VERITAS Data

Author

Archer, A., primary, Benbow, W., additional, Bird, R., additional, Brose, R., additional, Buchovecky, M., additional, Buckley, J. H., additional, Chromey, A. J., additional, Cui, W., additional, Falcone, A., additional, Feng, Q., additional, Finley, J. P., additional, Fortson, L., additional, Furniss, A., additional, Gent, A., additional, Gueta, O., additional, Hanna, D., additional, Hassan, T., additional, Hervet, O., additional, Holder, J., additional, Hughes, G., additional, Humensky, T. B., additional, Johnson, C. A., additional, Kaaret, P., additional, Kar, P., additional, Kelley-Hoskins, N., additional, Kertzman, M., additional, Kieda, D., additional, Krennrich, F., additional, Kumar, S., additional, Lang, M. J., additional, Lin, T. T. Y., additional, McCann, A., additional, Moriarty, P., additional, Mukherjee, R., additional, O’Brien, S., additional, Ong, R. A., additional, Otte, A. N., additional, Pandel, D., additional, Park, N., additional, Petrashyk, A., additional, Pohl, M., additional, Pueschel, E., additional, Quinn, J., additional, Ragan, K., additional, Richards, G. T., additional, Roache, E., additional, Sadeh, I., additional, Santander, M., additional, Scott, S. S., additional, Sembroski, G. H., additional, Shahinyan, K., additional, Sushch, I., additional, Tyler, J., additional, Wakely, S. P., additional, Weinstein, A., additional, Wells, R. M., additional, Wilcox, P., additional, Wilhelm, A., additional, Williams, D. A., additional, Williamson, T. J, additional, and Zitzer, B., additional

Published
2019
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34. Direct measurement of stellar angular diameters by the VERITAS Cherenkov telescopes

Author

Benbow, W., primary, Bird, R., additional, Brill, A., additional, Brose, R., additional, Chromey, A. J., additional, Daniel, M. K., additional, Feng, Q., additional, Finley, J. P., additional, Fortson, L., additional, Furniss, A., additional, Gillanders, G. H., additional, Giuri, C., additional, Gueta, O., additional, Hanna, D., additional, Halpern, J. P., additional, Hassan, T., additional, Holder, J., additional, Hughes, G., additional, Humensky, T. B., additional, Joyce, A. M., additional, Kaaret, P., additional, Kar, P., additional, Kelley-Hoskins, N., additional, Kertzman, M., additional, Kieda, D., additional, Krause, M., additional, Lang, M. J., additional, Lin, T. T. Y., additional, Maier, G., additional, Matthews, N., additional, Moriarty, P., additional, Mukherjee, R., additional, Nieto, D., additional, Nievas-Rosillo, M., additional, O’Brien, S., additional, Ong, R. A., additional, Park, N., additional, Petrashyk, A., additional, Pohl, M., additional, Pueschel, E., additional, Quinn, J., additional, Ragan, K., additional, Reynolds, P. T., additional, Richards, G. T., additional, Roache, E., additional, Rulten, C., additional, Sadeh, I., additional, Santander, M., additional, Sembroski, G. H., additional, Shahinyan, K., additional, Sushch, I., additional, Wakely, S. P., additional, Wells, R. M., additional, Wilcox, P., additional, Wilhelm, A., additional, Williams, D. A., additional, and Williamson, T. J., additional

Published
2019
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35. Extreme HBL behavior of Markarian 501 during 2012

Author

Ahnen, M. L., primary, Ansoldi, S., additional, Antonelli, L. A., additional, Arcaro, C., additional, Babić, A., additional, Banerjee, B., additional, Bangale, P., additional, Barresde Almeida, U., additional, Barrio, J. A., additional, BecerraGonzález, J., additional, Bednarek, W., additional, Bernardini, E., additional, Berti, A., additional, Bhattacharyya, W., additional, Blanch, O., additional, Bonnoli, G., additional, Carosi, R., additional, Carosi, A., additional, Chatterjee, A., additional, Colak, S. M., additional, Colin, P., additional, Colombo, E., additional, Contreras, J. L., additional, Cortina, J., additional, Covino, S., additional, Cumani, P., additional, Da Vela, P., additional, Dazzi, F., additional, De Angelis, A., additional, De Lotto, B., additional, Delfino, M., additional, Delgado, J., additional, Di ierro, F., additional, Doert, M., additional, Domínguez, A., additional, Dominis Prester, D., additional, Doro, M., additional, Eisenacher lawion, D., additional, Engelkemeier, M., additional, Fallah Ramazani, V., additional, Fernández-Barral, A., additional, Fidalgo, D., additional, Fonseca, M. V., additional, Font, L., additional, Fruck, C., additional, Galindo, D., additional, García López, R. J., additional, Garczarczyk, M., additional, Gaug, M., additional, Giammaria, P., additional, Godinović, N., additional, Gora, D., additional, Guberman, D., additional, Hadasch, D., additional, Hahn, A., additional, Hassan, T., additional, Hayashida, M., additional, Herrera, J., additional, Hose, J., additional, Hrupec, D., additional, Ishio, K., additional, Konno, Y., additional, Kubo, H., additional, Kushida, J., additional, Kuveždić, D., additional, Lelas, D., additional, Lindfors, E., additional, Lombardi, S., additional, Longo, F., additional, López, M., additional, Maggio, C., additional, Majumdar, P., additional, Makariev, M., additional, Maneva, G., additional, Manganaro, M., additional, Maraschi, L., additional, Mariotti, M., additional, Martínez, M., additional, Mazin, D., additional, Menzel, U., additional, Minev, M., additional, Miranda, J. M., additional, Mirzoyan, R., additional, Moralejo, A., additional, Moreno, V., additional, Moretti, E., additional, Nagayoshi, T., additional, Neustroev, V., additional, Niedzwiecki, A., additional, Nievas Rosillo, M., additional, Nigro, C., additional, Nilsson, K., additional, Ninci, D., additional, Nishijima, K., additional, Noda, K., additional, Nogués, L., additional, Paiano, S., additional, Palacio, J., additional, Paneque, D., additional, Paoletti, R., additional, Paredes, J. M., additional, Pedaletti, G., additional, Peresano, M., additional, Perri, L., additional, Persic, M., additional, Prada Moroni, P. G., additional, Prandini, E., additional, Puljak, I., additional, Garcia, J. R., additional, Reichardt, I., additional, Ribó, M., additional, Rico, J., additional, Righi, C., additional, Rugliancich, A., additional, Saito, T., additional, Satalecka, K., additional, Schroeder, S., additional, Schweizer, T., additional, Shore, S. N., additional, Sitarek, J., additional, Šnidarić, I., additional, Sobczynska, D., additional, Stamerra, A., additional, Strzys, M., additional, Surić, T., additional, Takalo, L., additional, Tavecchio, F., additional, Temnikov, P., additional, Terzić, T., additional, Teshima, M., additional, Torres-Albà, N., additional, Treves, A., additional, Tsujimoto, S., additional, Vanzo, G., additional, Vazquez Acosta, M., additional, Vovk, I., additional, Ward, J. E., additional, Will, M., additional, Zarić, D., additional, Arbet-Engels, A., additional, Baack, D., additional, Balbo, M., additional, Biland, A., additional, Blank, M., additional, Bretz, T., additional, Bruegge, K., additional, Bulinski, M., additional, Buss, J., additional, Dmytriiev, A., additional, Dorner, D., additional, Einecke, S., additional, Elsaesser, D., additional, Herbst, T., additional, Hildebrand, D., additional, Kortmann, L., additional, Linhoff, L., additional, Mahlke, M., additional, Mannheim, K., additional, Mueller, S. A., additional, Neise, D., additional, Neronov, A., additional, Noethe, M., additional, Oberkirch, J., additional, Paravac, A., additional, Rhode, W., additional, Schleicher, B., additional, Schulz, F., additional, Sedlaczek, K., additional, Shukla, A., additional, Sliusar, V., additional, Walter, R., additional, Archer, A., additional, Benbow, W., additional, Bird, R., additional, Brose, R., additional, Buckley, J. H., additional, Bugaev, V., additional, Christiansen, J. L., additional, Cui, W., additional, Daniel, M. K., additional, Falcone, A., additional, Feng, Q., additional, Finley, J. P., additional, Gillanders, G. H., additional, Gueta, O., additional, Hanna, D., additional, Hervet, O., additional, Holder, J., additional, Hughes, G., additional, Hütten, M., additional, Humensky, T. B., additional, Johnson, C. A., additional, Kaaret, P., additional, Kar, P., additional, Kelley-Hoskins, N., additional, Kertzman, M., additional, Kieda, D., additional, Krause, M., additional, Krennrich, F., additional, Kumar, S., additional, Lang, M. J., additional, Lin, T. T. Y., additional, Maier, G., additional, McArthur, S., additional, Moriarty, P., additional, Mukherjee, R., additional, O’Brien, S., additional, Ong, R. A., additional, Otte, A. N., additional, Park, N., additional, Petrashyk, A., additional, Pichel, A., additional, Pohl, M., additional, Quinn, J., additional, Ragan, K., additional, Reynolds, P. T., additional, Richards, G. T., additional, Roache, E., additional, Rovero, A. C., additional, Rulten, C., additional, Sadeh, I., additional, Santander, M., additional, Sembroski, G. H., additional, Shahinyan, K., additional, Sushch, I., additional, Tyler, J., additional, Wakely, S. P., additional, Weinstein, A., additional, Wells, R. M., additional, Wilcox, P., additional, Wilhel, A., additional, Williams, D. A., additional, J Williamson, T., additional, Zitzer, B., additional, Perri, M., additional, Verrecchia, F., additional, Leto, C., additional, Villata, M., additional, Raiteri, C. M., additional, Jorstad, S. G., additional, Larionov, V. M., additional, Blinov, D. A., additional, Grishina, T. S., additional, Kopatskaya, E. N., additional, Larionova, E. G., additional, Nikiforova, A. A., additional, Morozova, D. A., additional, Troitskaya, Yu. V., additional, Troitsky, I. S., additional, Kurtanidze, O. M., additional, Nikolashvili, M. G., additional, Kurtanidze, S. O., additional, Kimeridze, G. N., additional, Chigladze, R. A., additional, Strigachev, A., additional, Sadun, A. C., additional, Moody, J. W., additional, Chen, W. P., additional, Lin, H. C., additional, Acosta-Pulido, J. A., additional, Arévalo, M. J., additional, Carnerero, M. I., additional, González-Morales, P. A., additional, Manilla-Robles, A., additional, Jermak, H., additional, Steele, I., additional, Mundell, C., additional, Benítez, E., additional, Hiriart, D., additional, Smith, P. S., additional, Max-Moerbeck, W., additional, Readhead, A. C. S., additional, Richards, J. L., additional, Hovatta, T., additional, Lähteenmäki, A., additional, Tornikoski, M., additional, Tammi, J., additional, Georganopoulos, M., additional, and Baring, M. G., additional

Published
2018
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37. Multimessenger observations of a flaring blazar coincident with high-energy neutrino IceCube-170922A

Author

Aartsen, M. G., Ackermann, M., Adams, J., Aguilar, J. A., Ahlers, M., Ahrens, M., Al Samarai, I., Altmann, D., Andeen, K., Anderson, T., Ansseau, I., Anton, G., Arguelles, C., Auffenberg, J., Axani, S., Bagherpour, H., Bai, X., Barron, J. P., Barwick, S. W., Baum, V., Bay, R., Beatty, J. J., Tjus, J. Becker, Becker, K. -H, BenZvi, S., Berley, D., Bernardini, E., Besson, D. Z., Binder, G., Bindig, D., Blaufuss, E., Blot, S., Bohm, C., Borner, M., Bos, F., Boser, S., Botner, Olga, Bourbeau, E., Bourbeau, J., Bradascio, F., Braun, J., Brenzke, M., Bretz, H. -P, Bron, S., Brostean-Kaiser, J., Burgman, Alexander, Busse, R. S., Carver, T., Cheung, E., Chirkin, D., Christov, A., Clark, K., Classen, L., Coenders, S., Collin, G. H., Conrad, J. M., Coppin, P., Correa, P., Cowen, D. F., Cross, R., Dave, P., Day, M., de Andre, J. P. A. M., De Clercq, C., DeLaunay, J. J., Dembinski, H., De Ridder, S., Desiati, P., de Vries, K. D., de Wasseige, G., de With, M., DeYoung, T., Diaz-Velez, J. C., di Lorenzo, V., Dujmovic, H., Dumm, J. P., Dunkman, M., Dvorak, E., Eberhardt, B., Ehrhardt, T., Eichmann, B., Eller, P., Evenson, P. A., Fahey, S., Fazely, A. R., Felde, J., Filimonov, K., Finley, C., Flis, S., Franckowiak, A., Friedman, E., Fritz, A., Gaisser, T. K., Gallagher, J., Gerhardt, L., Ghorbani, K., Glauch, T., Glusenkamp, T., Goldschmidt, A., Gonzalez, J. G., Grant, D., Griffith, Z., Haack, C., Hallgren, Allan, Halzen, F., Hanson, K., Hebecker, D., Heereman, D., Helbing, K., Hellauer, R., Hickford, S., Hignight, J., Hill, G. C., Hoffman, K. D., Hoffmann, R., Hoinka, T., Hokanson-Fasig, B., Hoshina, K., Huang, F., Huber, M., Hultqvist, K., Hunnefeld, M., Hussain, R., In, S., Iovine, N., Ishihara, A., Jacobi, E., Japaridze, G. S., Jeong, M., Jero, K., Jones, B. J. P., Kalaczynski, P., Kang, W., Kappes, A., Kappesser, D., Karg, T., Karle, A., Katz, U., Kauer, M., Keivani, A., Kelley, J. L., Kheirandish, A., Kim, J., Kim, M., Kintscher, T., Kiryluk, J., Kittler, T., Klein, S. R., Koirala, R., Kolanoski, H., Kopke, L., Kopper, C., Kopper, S., Koschinsky, J. P., Koskinen, D. J., Kowalski, M., Krings, K., Kroll, M., Kruckl, G., Kunwar, S., Kurahashi, N., Kuwabara, T., Kyriacou, A., Labare, M., Lanfranchi, J. L., Larson, M. J., Lauber, F., Leonard, K., Lesiak-Bzdak, M., Leuermann, M., Liu, Q. R., Mariscal, C. J. Lozano, Lu, L., Lunemann, J., Luszczak, W., Madsen, J., Maggi, G., Mahn, K. B. M., Mancina, S., Maruyama, R., Mase, K., Maunu, R., Meagher, K., Medici, M., Meier, M., Menne, T., Merino, G., Meures, T., Miarecki, S., Micallef, J., Momente, G., Montaruli, T., Moore, R. W., Morse, R., Moulai, M., Nahnhauer, R., Nakarmi, P., Naumann, U., Neer, G., Niederhausen, H., Nowicki, S. C., Nygren, D. R., Pollmann, A. Obertacke, Olivas, A., O'Murchadha, A., O'Sullivan, E., Palczewski, T., Pandya, H., Pankova, D. V., Peiffer, P., Pepper, J. A., de los Heros, Carlos, Pieloth, D., Pinat, E., Plum, M., Price, P. B., Przybylski, G. T., Raab, C., Radel, L., Rameez, M., Rauch, L., Rawlins, K., Rea, I. C., Reimann, R., Relethford, B., Relich, M., Resconi, E., Rhode, W., Richman, M., Robertson, S., Rongen, M., Rott, C., Ruhe, T., Ryckbosch, D., Rysewyk, D., Safa, I., Salzer, T., Herrera, S. E. Sanchez, Sandrock, A., Sandroos, J., Santander, M., Sarkar, S., Satalecka, K., Schlunder, P., Schmidt, T., Schneider, A., Schoenen, S., Schoneberg, S., Schumacher, L., Sclafani, S., Seckel, D., Seunarine, S., Soedingrekso, J., Soldin, D., Song, M., Spiczak, G. M., Spiering, C., Stachurska, J., Stamatikos, M., Stanev, T., Stasik, A., Stein, R., Stettner, J., Steuer, A., Stezelberger, T., Stokstad, R. G., Stossl, A., Strotjohann, N. L., Stuttard, T., Sullivan, G. W., Sutherland, M., Taboada, I., Tatar, J., Tenholt, F., Ter-Antonyan, S., Terliuk, A., Tilav, S., Toale, P. A., Tobin, M. N., Toennis, C., Toscano, S., Tosi, D., Tselengidou, M., Tung, C. F., Turcati, A., Turley, C. F., Ty, B., Unger, Elisabeth, Usner, M., Vandenbroucke, J., Van Driessche, W., van Eijk, D., van Eijndhoven, N., Vanheule, S., van Santen, J., Vogel, E., Vraeghe, M., Walck, C., Wallace, A., Mallraff, M., Wandler, F. D., Wandkowsky, N., Waza, A., Weaver, C., Weiss, M. J., Wendt, C., Werthebach, J., Westerhoff, S., Whelan, B. J., Whitehorn, N., Wiebe, K., Wiebusch, C. H., Wille, L., Williams, D. R., Wills, L., Wolf, M., Wood, J., Wood, T. R., Woschnagg, K., Xu, D. L., Xu, X. W., Xu, Y., Yanez, J. P., Yodh, G., Yoshida, S., Yuan, T., Abdollahi, S., Ajello, M., Angioni, R., Baldini, L., Ballet, J., Barbiellini, G., Bastieri, D., Bechtol, K., Bellazzini, R., Berenji, B., Bissaldi, E., Blandford, R. D., Bonino, R., Bottacini, E., Bregeon, J., Bruel, P., Buehler, R., Burnett, T. H., Burns, E., Buson, S., Cameron, R. A., Caputo, R., Caraveo, P. A., Cavazzuti, E., Charles, E., Chen, S., Cheung, C. C., Chiang, J., Chiaro, G., Ciprini, S., Cohen-Tanugi, J., Conrad, J., Costantin, D., Cutini, S., D'Ammando, F., de Palma, F., Digel, S. W., Di Lalla, N., Di Mauro, M., Di Venere, L., Dominguez, A., Favuzzi, C., Fukazawa, Y., Funk, S., Fusco, P., Gargano, F., Gasparrini, D., Giglietto, N., Giomi, M., Giommi, P., Giordano, F., Giroletti, M., Glanzman, T., Green, D., Grenier, I. A., Grondin, M. -H, Guiriec, S., Harding, A. K., Hayashida, M., Hays, E., Hewitt, J. W., Horan, D., Johannesson, G., Kadler, M., Kensei, S., Kocevski, D., Krauss, F., Kreter, M., Kuss, M., La Mura, G., Larsson, S., Latronico, L., Lemoine-Goumard, M., Li, J., Longo, F., Loparco, F., Lovellette, M. N., Lubrano, P., Magill, J. D., Maldera, S., Malyshev, D., Manfreda, A., Mazziotta, M. N., McEnery, J. E., Meyer, M., Michelson, P. F., Mizuno, T., Monzani, M. E., Morselli, A., Moskalenko, I. V., Negro, M., Nuss, E., Ojha, R., Omodei, N., Orienti, M., Orlando, E., Palatiello, M., Paliya, V. S., Perkins, J. S., Persic, M., Pesce-Rollins, M., Piron, F., Porter, T. A., Principe, G., Raino, S., Rando, R., Rani, B., Razzano, M., Razzaque, S., Reimer, A., Reimer, O., Renault-Tinacci, N., Ritz, S., Rochester, L. S., Parkinson, P. M. Saz, Sgro, C., Siskind, E. J., Spandre, G., Spinelli, P., Suson, D. J., Tajima, H., Takahashi, M., Tanaka, Y., Thayer, J. B., Thompson, D. J., Tibaldo, L., Torres, D. F., Torresi, E., Tosti, G., Troja, E., Valverde, J., Vianello, G., Vogel, M., Wood, K., Wood, M., Zaharijas, G., Ahnen, M. L., Ansoldi, S., Antonelli, L. A., Arcaro, C., Baack, D., Babic, A., Banerjee, B., Bangale, P., de Almeida, U. Barres, Barrio, J. A., Gonzalez, J. Becerra, Bednarek, W., Berti, A., Bhattacharyya, W., Biland, A., Blanch, O., Bonnoli, G., Carosi, A., Carosi, R., Ceribella, G., Chatterjee, A., Colak, S. M., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Cumani, P., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Di Pierro, F., Prester, D. . Dominis, Dorner, D., Doro, M., Einecke, S., Elsaesser, D., Ramazani, V. Fallah, Fernandez-Barral, A., Fidalgo, D., Foffano, L., Pfrang, K., Fonseca, M. V., Font, L., Franceschini, A., Fruck, C., Galindo, D., Gallozzi, S., Lopez, R. J. Garcia, Garczarczyk, M., Gaug, M., Giammaria, P., Godinovic, N., Gora, D., Guberman, D., Hadasch, D., Hahn, A., Hassan, T., Herrera, J., Hose, J., Hrupec, D., Inoue, S., Ishio, K., Konno, Y., Kubo, H., Kushida, J., Lelas, D., Lindfors, E., Lombardi, S., Lopez, M., Maggio, C., Majumdar, P., Makariev, M., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Mariotti, M., Martinez, M., Masuda, S., Mazin, D., Minev, M., M, J. M., Mirzoyan, R., Moralejo, A., Moreno, V., Moretti, E., Nagayoshi, T., Neustroev, V., Niedzwiecki, A., Rosillo, M. Nievas, Nigro, C., Nilsson, K., Ninci, D., Nishijima, K., Noda, K., Nogues, L., Paiano, S., Palacio, J., Paneque, D., Paoletti, R., Paredes, J. M., Pedaletti, G., Peresano, M., Moroni, P. G. Prada, Prandini, E., Puljak, I., Garcia, J. Rodriguez, Reichardt, I., Ribo, M., Rico, J., Righi, C., Rugliancich, A., Saito, T., Schweizer, T., Sitarek, J., Snidaric, I., Sobczynska, D., Stamerra, A., Strzys, M., Suric, T., Tavecchio, F., Temnikov, P., Terzic, T., Teshima, M., Torres-Alba, N., Treves, A., Tsujimoto, S., Vanzo, G., Acosta, M. Vazquez, Vovk, I., Ward, J. E., Will, M., Zaric, D., Lucarelli, F., Tavani, M., Piano, G., Donnarumma, I., Pittori, C., Verrecchia, F., Bulgarelli, A., Caraveo, P., Cattaneo, P. W., Colafrancesco, S., Costa, E., Di Cocco, G., Ferrari, A., Gianotti, F., Giuliani, A., Lipari, P., Mereghetti, S., Pacciani, L., Paoletti, F., Parmiggiani, N., Pellizzoni, A., Picozza, P., Pilia, M., Rappoldi, A., Trois, A., Vercellone, S., Vittorini, V., Stanek, K. Z., Kochanek, C. S., Beacom, J. F., Thompson, T. A., Holoien, W. -S, Dong, S., Prieto, J. L., Shappee, B. J., Holmbo, S., Abeysekara, A. U., Albert, A., Alfaro, R., Alvarez, C., Arceo, R., Arteaga-Velazquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Becerril, A., Belmont-Moreno, E., Bernal, A., Caballero-Mora, K. S., Capistran, T., Carraminana, A., Casanova, S., Castillo, M., Cotti, U., Cotzomi, J., de Leon, S. Coutino, De Leon, C., De la Fuente, E., Hernandez, R. Diaz, Dichiara, S., Dingus, B. L., DuVernois, M. A., Ellsworth, R. W., Engel, K., Fiorino, D. W., Fleischhack, H., Fraija, N., Garcia-Gonzalez, J. A., Garfias, F., Munoz, A. Gonzalez, Gonzalez, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hona, B., Hueyotl-Zahuantitla, F., Hui, C. M., Huntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Kunde, G. J., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. Leon, Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Luna-Garcia, R., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martinez-Castro, J., Martinez-Huerta, H., Matthews, J. A., Miranda-Romagnoli, P., Moreno, E., Mostafa, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pelayo, R., Pretz, J., Perez-Perez, E. G., Ren, Z., Rho, C. D., Riviere, C., Rosa-Gonzalez, D., Rosenberg, M., Ruiz-Velasco, E., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Tibolla, O., Tollefson, K., Torres, I., Villasenor, L., Weisgarber, T., Werner, F., Yapici, T., Gaurang, Y., Zepeda, A., Zhou, H., Alvarez, J. D., Abdalla, H., Anguner, E. O., Armand, C., Backes, M., Becherini, Y., Berge, D., Bottcher, M., Boisson, C., Bolmont, J., Bonnefoy, S., Bordas, P., Brun, F., Buchele, M., Bulik, T., Caroff, S., Cerruti, M., Chakraborty, N., Chandra, S., Chen, A., Davids, I. D., Deil, C., Devin, J., Djannati-Atai, A., Egberts, K., Emery, G., Eschbach, S., Fiasson, A., Fontaine, G., Fussling, M., Gallant, Y. A., Gate, F., Giavitto, G., Glawion, D., Glicenstein, J. F., Gottschall, D., Haupt, M., Henri, G., Hinton, J. A., Hoischen, C., Holch, T. L., Huber, D., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jouvin, L., Jung-Richardt, I., Kerszberg, D., Khelifi, B., King, J., Klepser, S., Kluzniak, W., Komin, Nu., Kraus, M., Lefaucheur, J., Lemiere, A., Lenain, J. -P, Leser, E., Lohse, T., Lopez-Coto, R., Lorentz, M., Lypova, I., Marandon, V., Marti-Devesa, G. Guillem, Maurin, G., Mitchell, A. M. W., Moderski, R., Mohamed, M., Mohrmann, L., Moulin, E., Murach, T., de Naurois, M., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Ohm, S., Ostrowski, M., Oya, I., Panter, M., Parsons, R. D., Perennes, C., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokoph, H., Puhlhofer, G., Quirrenbach, A., Raab, S., Rauth, R., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Sanchez, D. A., Sasaki, M., Schlickeiser, R., Schussler, F., Schulz, A., Schwanke, U., Seglar-Arroyo, M., Shafi, N., Simoni, R., Sol, H., Stegmann, C., Steppa, C., Tavernier, T., Taylor, A. M., Tiziani, D., Trichard, C., Tsirou, M., van Eldik, C., van Rensburg, C., van Soelen, B., Veh, J., Vincent, P., Voisin, F., Wagner, S. J., Wagner, R. M., Wierzcholska, A., Zanin, R., Zdziarski, A. A., Zech, A., Ziegler, A., Zorn, J., Zywucka, N., Savchenko, V., Ferrigno, C., Bazzano, A., Diehl, R., Kuulkers, E., Laurent, P., Natalucci, L., Panessa, F., Rodi, J., Ubertini, P., Morokuma, T., Ohta, K., Tanaka, Y. T., Mori, H., Yamanaka, M., Kawabata, K. S., Utsumi, Y., Nakaoka, T., Kawabata, M., Nagashima, H., Yoshida, M., Matsuoka, Y., Itoh, R., Keel, W., Copperwheat, C., Steele, I., Cenko, S. B., Evans, P. A., Fox, D. B., Kennea, J. A., Marshall, F. E., Osborne, J. P., Tohuvavohu, A., Archer, A., Benbow, W., Bird, R., Brill, A., Brose, R., Buchovecky, M., Buckley, J. H., Bugaev, V., Christiansen, J. L., Connolly, M. P., Cui, W., Daniel, M. K., Errando, M., Falcone, A., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Gueta, O., Hutten, M., Hervet, O., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Lin, T. T. Y., Maier, G., McArthur, S., Moriarty, P., Mukherjee, R., Nieto, D., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pohl, M., Popkow, A., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rulten, C., Sadeh, I., Scott, S. S., Sembroski, G. H., Shahinyan, K., Sushch, I., Trepanier, S., Tyler, J., Vassiliev, V. V., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Zitzer, B., Tetarenko, A. J., Kimball, A. E., Miller-Jones, J. C. A., Sivakoff, G. R., Aartsen, M. G., Ackermann, M., Adams, J., Aguilar, J. A., Ahlers, M., Ahrens, M., Al Samarai, I., Altmann, D., Andeen, K., Anderson, T., Ansseau, I., Anton, G., Arguelles, C., Auffenberg, J., Axani, S., Bagherpour, H., Bai, X., Barron, J. P., Barwick, S. W., Baum, V., Bay, R., Beatty, J. J., Tjus, J. Becker, Becker, K. -H, BenZvi, S., Berley, D., Bernardini, E., Besson, D. Z., Binder, G., Bindig, D., Blaufuss, E., Blot, S., Bohm, C., Borner, M., Bos, F., Boser, S., Botner, Olga, Bourbeau, E., Bourbeau, J., Bradascio, F., Braun, J., Brenzke, M., Bretz, H. -P, Bron, S., Brostean-Kaiser, J., Burgman, Alexander, Busse, R. S., Carver, T., Cheung, E., Chirkin, D., Christov, A., Clark, K., Classen, L., Coenders, S., Collin, G. H., Conrad, J. M., Coppin, P., Correa, P., Cowen, D. F., Cross, R., Dave, P., Day, M., de Andre, J. P. A. M., De Clercq, C., DeLaunay, J. J., Dembinski, H., De Ridder, S., Desiati, P., de Vries, K. D., de Wasseige, G., de With, M., DeYoung, T., Diaz-Velez, J. C., di Lorenzo, V., Dujmovic, H., Dumm, J. P., Dunkman, M., Dvorak, E., Eberhardt, B., Ehrhardt, T., Eichmann, B., Eller, P., Evenson, P. A., Fahey, S., Fazely, A. R., Felde, J., Filimonov, K., Finley, C., Flis, S., Franckowiak, A., Friedman, E., Fritz, A., Gaisser, T. K., Gallagher, J., Gerhardt, L., Ghorbani, K., Glauch, T., Glusenkamp, T., Goldschmidt, A., Gonzalez, J. G., Grant, D., Griffith, Z., Haack, C., Hallgren, Allan, Halzen, F., Hanson, K., Hebecker, D., Heereman, D., Helbing, K., Hellauer, R., Hickford, S., Hignight, J., Hill, G. C., Hoffman, K. D., Hoffmann, R., Hoinka, T., Hokanson-Fasig, B., Hoshina, K., Huang, F., Huber, M., Hultqvist, K., Hunnefeld, M., Hussain, R., In, S., Iovine, N., Ishihara, A., Jacobi, E., Japaridze, G. S., Jeong, M., Jero, K., Jones, B. J. P., Kalaczynski, P., Kang, W., Kappes, A., Kappesser, D., Karg, T., Karle, A., Katz, U., Kauer, M., Keivani, A., Kelley, J. L., Kheirandish, A., Kim, J., Kim, M., Kintscher, T., Kiryluk, J., Kittler, T., Klein, S. R., Koirala, R., Kolanoski, H., Kopke, L., Kopper, C., Kopper, S., Koschinsky, J. P., Koskinen, D. J., Kowalski, M., Krings, K., Kroll, M., Kruckl, G., Kunwar, S., Kurahashi, N., Kuwabara, T., Kyriacou, A., Labare, M., Lanfranchi, J. L., Larson, M. J., Lauber, F., Leonard, K., Lesiak-Bzdak, M., Leuermann, M., Liu, Q. R., Mariscal, C. J. Lozano, Lu, L., Lunemann, J., Luszczak, W., Madsen, J., Maggi, G., Mahn, K. B. M., Mancina, S., Maruyama, R., Mase, K., Maunu, R., Meagher, K., Medici, M., Meier, M., Menne, T., Merino, G., Meures, T., Miarecki, S., Micallef, J., Momente, G., Montaruli, T., Moore, R. W., Morse, R., Moulai, M., Nahnhauer, R., Nakarmi, P., Naumann, U., Neer, G., Niederhausen, H., Nowicki, S. C., Nygren, D. R., Pollmann, A. Obertacke, Olivas, A., O'Murchadha, A., O'Sullivan, E., Palczewski, T., Pandya, H., Pankova, D. V., Peiffer, P., Pepper, J. A., de los Heros, Carlos, Pieloth, D., Pinat, E., Plum, M., Price, P. B., Przybylski, G. T., Raab, C., Radel, L., Rameez, M., Rauch, L., Rawlins, K., Rea, I. C., Reimann, R., Relethford, B., Relich, M., Resconi, E., Rhode, W., Richman, M., Robertson, S., Rongen, M., Rott, C., Ruhe, T., Ryckbosch, D., Rysewyk, D., Safa, I., Salzer, T., Herrera, S. E. Sanchez, Sandrock, A., Sandroos, J., Santander, M., Sarkar, S., Satalecka, K., Schlunder, P., Schmidt, T., Schneider, A., Schoenen, S., Schoneberg, S., Schumacher, L., Sclafani, S., Seckel, D., Seunarine, S., Soedingrekso, J., Soldin, D., Song, M., Spiczak, G. M., Spiering, C., Stachurska, J., Stamatikos, M., Stanev, T., Stasik, A., Stein, R., Stettner, J., Steuer, A., Stezelberger, T., Stokstad, R. G., Stossl, A., Strotjohann, N. L., Stuttard, T., Sullivan, G. W., Sutherland, M., Taboada, I., Tatar, J., Tenholt, F., Ter-Antonyan, S., Terliuk, A., Tilav, S., Toale, P. A., Tobin, M. N., Toennis, C., Toscano, S., Tosi, D., Tselengidou, M., Tung, C. F., Turcati, A., Turley, C. F., Ty, B., Unger, Elisabeth, Usner, M., Vandenbroucke, J., Van Driessche, W., van Eijk, D., van Eijndhoven, N., Vanheule, S., van Santen, J., Vogel, E., Vraeghe, M., Walck, C., Wallace, A., Mallraff, M., Wandler, F. D., Wandkowsky, N., Waza, A., Weaver, C., Weiss, M. J., Wendt, C., Werthebach, J., Westerhoff, S., Whelan, B. J., Whitehorn, N., Wiebe, K., Wiebusch, C. H., Wille, L., Williams, D. R., Wills, L., Wolf, M., Wood, J., Wood, T. R., Woschnagg, K., Xu, D. L., Xu, X. W., Xu, Y., Yanez, J. P., Yodh, G., Yoshida, S., Yuan, T., Abdollahi, S., Ajello, M., Angioni, R., Baldini, L., Ballet, J., Barbiellini, G., Bastieri, D., Bechtol, K., Bellazzini, R., Berenji, B., Bissaldi, E., Blandford, R. D., Bonino, R., Bottacini, E., Bregeon, J., Bruel, P., Buehler, R., Burnett, T. H., Burns, E., Buson, S., Cameron, R. A., Caputo, R., Caraveo, P. A., Cavazzuti, E., Charles, E., Chen, S., Cheung, C. C., Chiang, J., Chiaro, G., Ciprini, S., Cohen-Tanugi, J., Conrad, J., Costantin, D., Cutini, S., D'Ammando, F., de Palma, F., Digel, S. W., Di Lalla, N., Di Mauro, M., Di Venere, L., Dominguez, A., Favuzzi, C., Fukazawa, Y., Funk, S., Fusco, P., Gargano, F., Gasparrini, D., Giglietto, N., Giomi, M., Giommi, P., Giordano, F., Giroletti, M., Glanzman, T., Green, D., Grenier, I. A., Grondin, M. -H, Guiriec, S., Harding, A. K., Hayashida, M., Hays, E., Hewitt, J. W., Horan, D., Johannesson, G., Kadler, M., Kensei, S., Kocevski, D., Krauss, F., Kreter, M., Kuss, M., La Mura, G., Larsson, S., Latronico, L., Lemoine-Goumard, M., Li, J., Longo, F., Loparco, F., Lovellette, M. N., Lubrano, P., Magill, J. D., Maldera, S., Malyshev, D., Manfreda, A., Mazziotta, M. N., McEnery, J. E., Meyer, M., Michelson, P. F., Mizuno, T., Monzani, M. E., Morselli, A., Moskalenko, I. V., Negro, M., Nuss, E., Ojha, R., Omodei, N., Orienti, M., Orlando, E., Palatiello, M., Paliya, V. S., Perkins, J. S., Persic, M., Pesce-Rollins, M., Piron, F., Porter, T. A., Principe, G., Raino, S., Rando, R., Rani, B., Razzano, M., Razzaque, S., Reimer, A., Reimer, O., Renault-Tinacci, N., Ritz, S., Rochester, L. S., Parkinson, P. M. Saz, Sgro, C., Siskind, E. J., Spandre, G., Spinelli, P., Suson, D. J., Tajima, H., Takahashi, M., Tanaka, Y., Thayer, J. B., Thompson, D. J., Tibaldo, L., Torres, D. F., Torresi, E., Tosti, G., Troja, E., Valverde, J., Vianello, G., Vogel, M., Wood, K., Wood, M., Zaharijas, G., Ahnen, M. L., Ansoldi, S., Antonelli, L. A., Arcaro, C., Baack, D., Babic, A., Banerjee, B., Bangale, P., de Almeida, U. Barres, Barrio, J. A., Gonzalez, J. Becerra, Bednarek, W., Berti, A., Bhattacharyya, W., Biland, A., Blanch, O., Bonnoli, G., Carosi, A., Carosi, R., Ceribella, G., Chatterjee, A., Colak, S. M., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Cumani, P., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Di Pierro, F., Prester, D. . Dominis, Dorner, D., Doro, M., Einecke, S., Elsaesser, D., Ramazani, V. Fallah, Fernandez-Barral, A., Fidalgo, D., Foffano, L., Pfrang, K., Fonseca, M. V., Font, L., Franceschini, A., Fruck, C., Galindo, D., Gallozzi, S., Lopez, R. J. Garcia, Garczarczyk, M., Gaug, M., Giammaria, P., Godinovic, N., Gora, D., Guberman, D., Hadasch, D., Hahn, A., Hassan, T., Herrera, J., Hose, J., Hrupec, D., Inoue, S., Ishio, K., Konno, Y., Kubo, H., Kushida, J., Lelas, D., Lindfors, E., Lombardi, S., Lopez, M., Maggio, C., Majumdar, P., Makariev, M., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Mariotti, M., Martinez, M., Masuda, S., Mazin, D., Minev, M., M, J. M., Mirzoyan, R., Moralejo, A., Moreno, V., Moretti, E., Nagayoshi, T., Neustroev, V., Niedzwiecki, A., Rosillo, M. Nievas, Nigro, C., Nilsson, K., Ninci, D., Nishijima, K., Noda, K., Nogues, L., Paiano, S., Palacio, J., Paneque, D., Paoletti, R., Paredes, J. M., Pedaletti, G., Peresano, M., Moroni, P. G. Prada, Prandini, E., Puljak, I., Garcia, J. Rodriguez, Reichardt, I., Ribo, M., Rico, J., Righi, C., Rugliancich, A., Saito, T., Schweizer, T., Sitarek, J., Snidaric, I., Sobczynska, D., Stamerra, A., Strzys, M., Suric, T., Tavecchio, F., Temnikov, P., Terzic, T., Teshima, M., Torres-Alba, N., Treves, A., Tsujimoto, S., Vanzo, G., Acosta, M. Vazquez, Vovk, I., Ward, J. E., Will, M., Zaric, D., Lucarelli, F., Tavani, M., Piano, G., Donnarumma, I., Pittori, C., Verrecchia, F., Bulgarelli, A., Caraveo, P., Cattaneo, P. W., Colafrancesco, S., Costa, E., Di Cocco, G., Ferrari, A., Gianotti, F., Giuliani, A., Lipari, P., Mereghetti, S., Pacciani, L., Paoletti, F., Parmiggiani, N., Pellizzoni, A., Picozza, P., Pilia, M., Rappoldi, A., Trois, A., Vercellone, S., Vittorini, V., Stanek, K. Z., Kochanek, C. S., Beacom, J. F., Thompson, T. A., Holoien, W. -S, Dong, S., Prieto, J. L., Shappee, B. J., Holmbo, S., Abeysekara, A. U., Albert, A., Alfaro, R., Alvarez, C., Arceo, R., Arteaga-Velazquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Becerril, A., Belmont-Moreno, E., Bernal, A., Caballero-Mora, K. S., Capistran, T., Carraminana, A., Casanova, S., Castillo, M., Cotti, U., Cotzomi, J., de Leon, S. Coutino, De Leon, C., De la Fuente, E., Hernandez, R. Diaz, Dichiara, S., Dingus, B. L., DuVernois, M. A., Ellsworth, R. W., Engel, K., Fiorino, D. W., Fleischhack, H., Fraija, N., Garcia-Gonzalez, J. A., Garfias, F., Munoz, A. Gonzalez, Gonzalez, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hona, B., Hueyotl-Zahuantitla, F., Hui, C. M., Huntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Kunde, G. J., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. Leon, Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Luna-Garcia, R., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martinez-Castro, J., Martinez-Huerta, H., Matthews, J. A., Miranda-Romagnoli, P., Moreno, E., Mostafa, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pelayo, R., Pretz, J., Perez-Perez, E. G., Ren, Z., Rho, C. D., Riviere, C., Rosa-Gonzalez, D., Rosenberg, M., Ruiz-Velasco, E., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Tibolla, O., Tollefson, K., Torres, I., Villasenor, L., Weisgarber, T., Werner, F., Yapici, T., Gaurang, Y., Zepeda, A., Zhou, H., Alvarez, J. D., Abdalla, H., Anguner, E. O., Armand, C., Backes, M., Becherini, Y., Berge, D., Bottcher, M., Boisson, C., Bolmont, J., Bonnefoy, S., Bordas, P., Brun, F., Buchele, M., Bulik, T., Caroff, S., Cerruti, M., Chakraborty, N., Chandra, S., Chen, A., Davids, I. D., Deil, C., Devin, J., Djannati-Atai, A., Egberts, K., Emery, G., Eschbach, S., Fiasson, A., Fontaine, G., Fussling, M., Gallant, Y. A., Gate, F., Giavitto, G., Glawion, D., Glicenstein, J. F., Gottschall, D., Haupt, M., Henri, G., Hinton, J. A., Hoischen, C., Holch, T. L., Huber, D., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jouvin, L., Jung-Richardt, I., Kerszberg, D., Khelifi, B., King, J., Klepser, S., Kluzniak, W., Komin, Nu., Kraus, M., Lefaucheur, J., Lemiere, A., Lenain, J. -P, Leser, E., Lohse, T., Lopez-Coto, R., Lorentz, M., Lypova, I., Marandon, V., Marti-Devesa, G. Guillem, Maurin, G., Mitchell, A. M. W., Moderski, R., Mohamed, M., Mohrmann, L., Moulin, E., Murach, T., de Naurois, M., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Ohm, S., Ostrowski, M., Oya, I., Panter, M., Parsons, R. D., Perennes, C., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokoph, H., Puhlhofer, G., Quirrenbach, A., Raab, S., Rauth, R., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Sanchez, D. A., Sasaki, M., Schlickeiser, R., Schussler, F., Schulz, A., Schwanke, U., Seglar-Arroyo, M., Shafi, N., Simoni, R., Sol, H., Stegmann, C., Steppa, C., Tavernier, T., Taylor, A. M., Tiziani, D., Trichard, C., Tsirou, M., van Eldik, C., van Rensburg, C., van Soelen, B., Veh, J., Vincent, P., Voisin, F., Wagner, S. J., Wagner, R. M., Wierzcholska, A., Zanin, R., Zdziarski, A. A., Zech, A., Ziegler, A., Zorn, J., Zywucka, N., Savchenko, V., Ferrigno, C., Bazzano, A., Diehl, R., Kuulkers, E., Laurent, P., Natalucci, L., Panessa, F., Rodi, J., Ubertini, P., Morokuma, T., Ohta, K., Tanaka, Y. T., Mori, H., Yamanaka, M., Kawabata, K. S., Utsumi, Y., Nakaoka, T., Kawabata, M., Nagashima, H., Yoshida, M., Matsuoka, Y., Itoh, R., Keel, W., Copperwheat, C., Steele, I., Cenko, S. B., Evans, P. A., Fox, D. B., Kennea, J. A., Marshall, F. E., Osborne, J. P., Tohuvavohu, A., Archer, A., Benbow, W., Bird, R., Brill, A., Brose, R., Buchovecky, M., Buckley, J. H., Bugaev, V., Christiansen, J. L., Connolly, M. P., Cui, W., Daniel, M. K., Errando, M., Falcone, A., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Gueta, O., Hutten, M., Hervet, O., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Lin, T. T. Y., Maier, G., McArthur, S., Moriarty, P., Mukherjee, R., Nieto, D., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pohl, M., Popkow, A., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rulten, C., Sadeh, I., Scott, S. S., Sembroski, G. H., Shahinyan, K., Sushch, I., Trepanier, S., Tyler, J., Vassiliev, V. V., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Zitzer, B., Tetarenko, A. J., Kimball, A. E., Miller-Jones, J. C. A., and Sivakoff, G. R.

Abstract

INTRODUCTION Neutrinos are tracers of cosmic-ray acceleration: electrically neutral and traveling at nearly the speed of light, they can escape the densest environments and may be traced back to their source of origin. High-energy neutrinos are expected to be produced in blazars: intense extragalactic radio, optical, x-ray, and, in some cases, γ-ray sources characterized by relativistic jets of plasma pointing close to our line of sight. Blazars are among the most powerful objects in the Universe and are widely speculated to be sources of high-energy cosmic rays. These cosmic rays generate high-energy neutrinos and γ-rays, which are produced when the cosmic rays accelerated in the jet interact with nearby gas or photons. On 22 September 2017, the cubic-kilometer IceCube Neutrino Observatory detected a ~290-TeV neutrino from a direction consistent with the flaring γ-ray blazar TXS 0506+056. We report the details of this observation and the results of a multiwavelength follow-up campaign. RATIONALE Multimessenger astronomy aims for globally coordinated observations of cosmic rays, neutrinos, gravitational waves, and electromagnetic radiation across a broad range of wavelengths. The combination is expected to yield crucial information on the mechanisms energizing the most powerful astrophysical sources. That the production of neutrinos is accompanied by electromagnetic radiation from the source favors the chances of a multiwavelength identification. In particular, a measured association of high-energy neutrinos with a flaring source of γ-rays would elucidate the mechanisms and conditions for acceleration of the highest-energy cosmic rays. The discovery of an extraterrestrial diffuse flux of high-energy neutrinos, announced by IceCube in 2013, has characteristic properties that hint at contributions from extragalactic sources, although the individual sources remain as yet unidentified. Continuously monitoring the entire sky for astrophysical neutrinos, IceCube provides

Published
2018
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38. Multiwavelength Observations of the Blazar BL Lacertae: A New Fast TeV Gamma-Ray Flare

Author

Department of Energy (US), National Science Foundation (US), Smithsonian Institution, National Research Council of Canada, National Aeronautics and Space Administration (US), Russian Foundation for Basic Research, Russian Government, Alexander von Humboldt Foundation, Academy of Finland, Ministerio de Economía y Competitividad (España), European Commission, Junta de Andalucía, Russian Science Foundation, Abeysekara, A. U., Benbow, W., Bird, R., Brantseg, T., Brose, R., Buchovecky, M., Buckley, J. H., Bugaev, V., Connolly, M. P., Cui, W., Daniel, M. K., Falcone, A., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Gillanders, G. H., Gunawardhana, I., Hütten, M., Hanna, D., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kertzman, M., Krennrich, F., Lang, M. J., Lin, T.T.Y., McArthur, S., Moriarty, P., Mukherjee, R., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pohl, M., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Williams, D. A., Zitzer, B., VERITAS Collaboration, Jorstad, S.G., Marscher, Alan P., Lister, Matthew L., Kovalev, Y. Y., Pushkarev, A.B., Savolainen, T., Agudo, Iván, Molina, Sol, Gómez, José L., Larionov, Valeri M., Borman, G.A., Mokrushina, A. A., Tornikoski, Merja, Lähteenmäki, Anne, Chamani, W., Enestam, S., Kiehlmann, S., Hovatta, T., Smith, P. S., Pontrelli, P., Department of Energy (US), National Science Foundation (US), Smithsonian Institution, National Research Council of Canada, National Aeronautics and Space Administration (US), Russian Foundation for Basic Research, Russian Government, Alexander von Humboldt Foundation, Academy of Finland, Ministerio de Economía y Competitividad (España), European Commission, Junta de Andalucía, Russian Science Foundation, Abeysekara, A. U., Benbow, W., Bird, R., Brantseg, T., Brose, R., Buchovecky, M., Buckley, J. H., Bugaev, V., Connolly, M. P., Cui, W., Daniel, M. K., Falcone, A., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Gillanders, G. H., Gunawardhana, I., Hütten, M., Hanna, D., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kertzman, M., Krennrich, F., Lang, M. J., Lin, T.T.Y., McArthur, S., Moriarty, P., Mukherjee, R., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pohl, M., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Williams, D. A., Zitzer, B., VERITAS Collaboration, Jorstad, S.G., Marscher, Alan P., Lister, Matthew L., Kovalev, Y. Y., Pushkarev, A.B., Savolainen, T., Agudo, Iván, Molina, Sol, Gómez, José L., Larionov, Valeri M., Borman, G.A., Mokrushina, A. A., Tornikoski, Merja, Lähteenmäki, Anne, Chamani, W., Enestam, S., Kiehlmann, S., Hovatta, T., Smith, P. S., and Pontrelli, P.

Abstract

Combined with measurements made by very-long-baseline interferometry, the observations of fast TeV gamma-ray flares probe the structure and emission mechanism of blazar jets. However, only a handful of such flares have been detected to date, and only within the last few years have these flares been observed from lower-frequency-peaked BL Lac objects and flat-spectrum radio quasars. We report on a fast TeV gamma-ray flare from the blazar BL Lacertae observed by the Very Energetic Radiation Imaging Telescope Array System (VERITAS). with a rise time of ∼2.3 hr and a decay time of ∼36 min. The peak flux above 200 GeV is (4.2 ± 0.6) ×10 photon m s measured with a 4-minute-binned light curve, corresponding to ∼180% of the flux that is observed from the Crab Nebula above the same energy threshold. Variability contemporaneous with the TeV gamma-ray flare was observed in GeV gamma-ray, X-ray, and optical flux, as well as in optical and radio polarization. Additionally, a possible moving emission feature with superluminal apparent velocity was identified in Very Long Baseline Array observations at 43 GHz, potentially passing the radio core of the jet around the time of the gamma-ray flare. We discuss the constraints on the size, Lorentz factor, and location of the emitting region of the flare, and the interpretations with several theoretical models that invoke relativistic plasma passing stationary shocks.© 2018. The American Astronomical Society. All rights reserved.

Published
2018

39. A Very High Energy γ-Ray Survey toward the Cygnus Region of the Galaxy

Author

Abeysekara, A. U., primary, Archer, A., additional, Aune, T., additional, Benbow, W., additional, Bird, R., additional, Brose, R., additional, Buchovecky, M., additional, Bugaev, V., additional, Cui, W., additional, Daniel, M. K., additional, Falcone, A., additional, Feng, Q., additional, Finley, J. P., additional, Fleischhack, H., additional, Flinders, A., additional, Fortson, L., additional, Furniss, A., additional, Gotthelf, E. V., additional, Grube, J., additional, Hanna, D., additional, Hervet, O., additional, Holder, J., additional, Huang, K., additional, Hughes, G., additional, Humensky, T. B., additional, Hütten, M., additional, Johnson, C. A., additional, Kaaret, P., additional, Kar, P., additional, Kelley-Hoskins, N., additional, Kertzman, M., additional, Kieda, D., additional, Krause, M., additional, Kumar, S., additional, Lang, M. J., additional, Lin, T. T. Y., additional, Maier, G., additional, McArthur, S., additional, Moriarty, P., additional, Mukherjee, R., additional, O’Brien, S., additional, Ong, R. A., additional, Otte, A. N., additional, Pandel, D., additional, Park, N., additional, Petrashyk, A., additional, Pohl, M., additional, Popkow, A., additional, Pueschel, E., additional, Quinn, J., additional, Ragan, K., additional, Reynolds, P. T., additional, Richards, G. T., additional, Roache, E., additional, Rousselle, J., additional, Rulten, C., additional, Sadeh, I., additional, Santander, M., additional, Sembroski, G. H., additional, Shahinyan, K., additional, Tyler, J., additional, Vassiliev, V. V., additional, Wakely, S. P., additional, Ward, J. E., additional, Weinstein, A., additional, Wells, R. M., additional, Wilcox, P., additional, Wilhelm, A., additional, Williams, D. A., additional, and Zitzer, B., additional

Published
2018
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46. Air breathing minimizes post-exercise lactate load in the tropical Pacific tarpon, Megalops cyprinoides Broussonet 1782 but oxygen debt is repaid by aquatic breathing

Author

Wells, R. M. G., Baldwin, J., Seymour, R. S., Christian, Keith A., Farrell, A. P., Wells, R. M. G., Baldwin, J., Seymour, R. S., Christian, Keith A., and Farrell, A. P.

Abstract

Swimming in a flume at reduced water pO2 resulted in muscle and blood lactate levels in Pacific tarpon Megalops cyprinoides that were significantly higher when fish did not have access to air. Blood glucose and haematological variables were unchanged throughout the regimes of exercise at two swimming speeds and hypoxia. Strenuous exercise with bouts of burst swimming, however, resulted in both high blood lactate and glucose, and perturbed haematological status with elevated haemoglobin and reduced mean cell-haemoglobin concentration. Post-exercise recovery was achieved through aquatic breathing rather than by air breathing. The air-breathing organ in Pacific tarpon therefore prolonged aerobic activity, but gill breathing was used to repay oxygen debt.

Published
2007

47. Continuous measurement of oxygen tensions in the air-breathing organ of Pacific tarpon (Megalops cyprinoides) in relation to aquatic hypoxia and exercise

Author

Seymour, R. S., Farrell, A. P., Christian, Keith A., Clark, T., Bennett, M., Wells, R. M. G., Baldwin, J., Seymour, R. S., Farrell, A. P., Christian, Keith A., Clark, T., Bennett, M., Wells, R. M. G., and Baldwin, J.

Abstract

The Pacific tarpon is an elopomorph teleost fish with an air-breathing organ (ABO) derived from a physostomous gas bladder. Oxygen partial pressure (PO2) in the ABO was measured on juveniles (238 g) with fiberoptic sensors during exposure to selected aquatic PO2 and swimming speeds. At slow speed (0.65 BL s(-1)), progressive aquatic hypoxia triggered the first breath at a mean PO, of 8.3 kPa. Below this, opercular movements declined sharply and visibly ceased in most fish below 6 kPa. At aquatic PO, of 6.1 kPa and swimming slowly, mean air-breathing frequency was 0.73 min', ABO was PO2 10.9) kPa, breath volume was 23.8 ml kg(-1) rate of oxygen uptake from the ABO was 1. 19 mi kg(-1) min(-1), and oxygen uptake per breath was 2.32 ml kg(-1). At the fastest experimental speed (2.4 BL s(-1)) at 6.1 kPa, ABO oxygen uptake increased to about 1.90 ml kg-1 min(-1), through a variable combination of breathing frequency and oxygen uptake per breath. In normoxic water, tarpon rarely breathed air and apparently closed down ABO perfusion, indicated by a drop in ABO oxygen uptake rate to about 1% of that in hypoxic water. This occurred at a wide range of ABO PO2 (1.7-26.4 kPa), suggesting that oxygen level in the ABO was not regulated by intrinsic receptors.

Published
2007

48. Changes in cardiac output during swimming and aquatic hypoxia in the air-breathing Pacific tarpon

Author

Clark, T. D., Seymour, R. S., Christian, Keith A., Wells, R. M. G., Baldwin, J., Farrell, A. P., Clark, T. D., Seymour, R. S., Christian, Keith A., Wells, R. M. G., Baldwin, J., and Farrell, A. P.

Abstract

Pacific tarpon (Megalops cyprinoides) use a modified gas bladder as an air-breathing organ (ABO). We examined changes in cardiac output (V-b) associated with increases in air-breathing that accompany exercise and aquatic hypoxia. Juvenile (0.49 kg) and adult (1.21 kg) tarpon were allowed to recover in a swim flume at 27 'C after being instrumented with a Doppler flow probe around the ventral aorta to monitor band with a fibre-optic o en sensor in the ABO to monitor air-breathing frequency. Under normoxic conditions and in both juveniles and adults, routine air-breathing frequency was 0.03 breaths min(-1) and V-b was about 15 mL min(-1) kg(-1). Normoxic exercise (swimming at about 1.1 body lengths s(-1)) increased air-breathing frequency by 8-fold in both groups (reaching 0.23 breaths min(-1)) and increased Rb by 3-fold for juveniles and 2-fold for adults. Hypoxic exposure (2 kPa O-2) at rest increased air-breathing frequency 19-fold (to around 0.53 breaths min(-1)) in both groups, and while V-b again increased 3-fold in resting juvenile fish, V-b was unchanged in resting adult fish. Exercise in hypoxia increased air-breathing frequency 35-fold (to 0.95 breaths min(-1)) in comparison with resting normoxic fish. While juvenile fish increased V-b nearly 2-fold with exercise in hypoxia, adult fish maintained the same V-b irrespective of exercise state and became agitated in comparison. These results imply that air-breathing during exercise and hypoxia can benefit oxygen delivery, but to differing degrees in juvenile and adult tarpon. We discuss this difference in the context of myocardial oxygen supply.

Published
2007

49. Red blood cell function and haematology in two tropical freshwater fishes from Australia

Author

Wells, R. M. G., Baldwin, J., Seymour, R. S., Christian, Keith A., Brittain, T., Wells, R. M. G., Baldwin, J., Seymour, R. S., Christian, Keith A., and Brittain, T.

Abstract

Salmon catfish and tarpon occur in habitats that periodically become deficient in oxygen resulting in high mortalities of other fish species. The water-breathing catfish, Arius leptaspis, and the facultative air-breathing tarpon, Megalops cyprinoides, both have high haemoglobin and haematocrit, and the oxygen carrying capacity in the air-breather is exceptionally high (15.6 +/- 1.2 vol%). Iso-pH oxygen equilibria of the red blood cells at 25 degrees C revealed high affinity (P-50 = 9 mmHg, pH 7.4) and co-operativity (n(50) > 2.2, pH 7.4) in the catfish, and contrasted with low affinity (P-50 = 32 mmHg, pH 7.4) and co-operativity (n(50) approximate to 1) in the air-breathing tarpon. Oxygen binding was further distinguished by relative pH insensitivity (Bohr factor, circle divide = Delta log P-50/Delta log pH = -0.22) in the catfish, compared with a significant Bohr effect in the tarpon (circle divide = -0.96). The potential for modulation of haemoglobin-oxygen affinity was indicated by a high ratio of GTP to ATP in the erythrocytes of the catfish, whereas regulation in the tarpon appeared due to ATP alone. Differences in blood respiratory functions between the two species are likely to reflect reduced opportunity for activity under extreme hypoxia in the catfish.

Published
2005

50. Oxygen transport capacity in the air-breathing fish, Megalops cyprinoides: compensations for strenuous exercise

Author

Wells, R. M. G., Baldwin, J., Seymour, R. S., Baudinette, R. V., Christian, Keith A., Bennett, M. B., Wells, R. M. G., Baldwin, J., Seymour, R. S., Baudinette, R. V., Christian, Keith A., and Bennett, M. B.

Abstract

Tarpon have high resting or routine hematocrits (Hct) (37.6+/-3.4%) and hemoglobin concentrations (120.6+/-7.3 gl-1) that increased significantly following bouts of angling-induced exercise (51.9+/-3.7% and 142.8+/-13.5 gl-1, respectively). Strenuous exercise was accompanied by an approximately tenfold increase in blood lactate and a muscle metabolite profile indicative of a high energy demand teleost. Routine blood values were quickly restored only when this facultative air-breathing fish was given access to atmospheric air. In vitro studies of oxygen transport capacity, a function of carrying capacity and viscosity, revealed that the optimal Hct range corresponded to that observed in fish under routine behaviour. During strenuous exercise however, further increase in viscosity was largely offset by a pronounced reduction in the shear-dependence of blood which conformed closely to an ideal Newtonian fluid. The mechanism for this behaviour of the erythrocytes appears to involve the activation of surface adrenergic receptors because pre-treatment with propranolol abolished the response. High levels of activity in tarpon living in hypoxic habitats are therefore supported by an elevated Hct with adrenergically mediated viscosity reduction, and air-breathing behaviour that enables rapid metabolic recovery.

Published
2003

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