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1. The Fourth Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope

Author

M. Ajello, R. Angioni, M. Axelsson, J. Ballet, G. Barbiellini, D. Bastieri, J. Becerra Gonzalez, R. Bellazzini, E. Bissaldi, E. D. Bloom, R. Bonino, E. Bottacini, P. Bruel, S. Buson, F. Cafardo, R. A. Cameron, E. Cavazzuti, S. Chen, C. C. Cheung, S. Ciprini, D. Costantin, S. Cutini, F. D’Ammando, P. de la Torre Luque, R. de Menezes, F. de Palma, A. Desai, N. Di Lalla, L. Di Venere, A. Domínguez, F. Fana Dirirsa, E. C. Ferrara, J. Finke, A. Franckowiak, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, S. Garrappa, D. Gasparrini, N. Giglietto, F. Giordano, M. Giroletti, D. Green, I. A. Grenier, S. Guiriec, S. Harita, E. Haywood, D. Horan, R. Itoh, G. Jóhannesson, M. Kovac’evic’, F. Krauss, M. Kreter, M. Kuss, S. Larsson, C. Leto, J. Li, I. Liodakis, F. Longo, F. Loparco, B. Lott, M. N. Lovellette, P. Lubrano, G. M. Madejski, S. Maldera, A. Manfreda, G. Martí-Devesa, F. Massaro, M. N. Mazziotta, I. Mereu, M. Meyer, G. Migliori, N. Barrios, T. Mizuno, M. E. Monzani, A. Morselli, I. V. Moskalenko, M. Negro, R. Nemmen, E. Nuss, L. S. Ojha, R. Ojha, N. Omodei, M. Orienti, E. Orlando, J. F. Ormes, V. S. Paliya, Z. Pei, H. Peña-Herazo, M. Persic, M. Pesce-Rollins, L. Petrov, F. Piron, H. Poon, G. Principe, S. Rainò, R. Rando, B. Rani, M. Razzano, S. Razzaque, A. Reimer, O. Reimer, F. K. Schinzel, D. Serini, C. Sgrò, E. J. Siskind, G. Spandre, P. Spinelli, D. J. Suson, Y. Tachibana, D. J. Thompson, D. F. Torres, E. Torresi, E. Troja, J. Valverde, P. van Zyl, and M. Yassine

Subjects
Astrophysics, Astronomy
Abstract

The fourth catalog of active galactic nuclei (AGNs) detected by the Fermi Gamma-ray Space Telescope Large Area Telescope (4LAC) between 2008 August 4 and 2016 August 2 contains $2863$ objects located at high Galactic latitudes (| b| > 10^9). It includes 85% more sources than the previous 3LAC catalog based on 4 yr of data. AGNs represent at least 79% of the high-latitude sources in the fourth Fermi-Large Area Telescope Source Catalog (4FGL), which covers the energy range from 50 MeV to 1 TeV. In addition, 344 gamma-ray AGNs are found at low Galactic latitudes. Most of the 4LAC AGNs are blazars (98%), while the remainder are other types of AGNs. The blazar population consists of 24% Flat Spectrum Radio Quasars (FSRQs), 38% BL Lac-type objects, and 38% blazar candidates of unknown types (BCUs). On average, FSRQs display softer spectra and stronger variability in the gamma-ray band than BL Lacs do, confirming previous findings. All AGNs detected by ground-based atmospheric Cerenkov telescopes are also found in the 4LAC.

Published
2020
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2. The Fourth Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope

Author

M. Ajello, R. Angioni, M. Axelsson, J. Ballet, G. Barbiellini, D. Bastieri, J. Becerra Gonzalez, R. Bellazzini, E. Bissaldi, E. D. Bloom, R. Bonino, E. Bottacini, P. Bruel, S. Buson, F. Cafardo, R. A. Cameron, E. Cavazzuti, S. Chen, C. C. Cheung, S. Ciprini, D. Costantin, S. Cutini, F. D'Ammando, P. de la Torre Luque, R. de Menezes, F. de Palma, A. Desai, N. Di Lalla, L. Di Venere, A. Dominguez, F. Fana Dirirsa, E. C. Ferrara, J. Finke, A. Franckowiak, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, S. Garrappa, D. Gasparrini, N. Giglietto, F. Giordano, M. Giroletti, D. Green, I. A. Grenier, S. Guiriec, S. Harita, E. Hays, D. Horan, R. Itoh, G. Jóhannesson, M. Kovac’evic’, F. Krauss, M. Kreter, M. Kuss, S. Larsson, C. Leto, J. Li, I. Liodakis, F. Longo, F. Loparco, B. Lott, M. N. Lovellette, P. Lubrano, G. M. Madejski, S. Maldera, A. Manfreda, G. Martí-Devesa, F. Massaro, M. N. Mazziotta, I. Mereu, M. Meyer, G. Migliori, N. Mirabal, T. Mizuno, M. E. Monzani, A. Morselli, I. V. Moskalenko, M. Negro, R. Nemmen, E. Nuss, L. S. Ojha, R. Ojha, N. Omodei, M. Orienti, E. Orlando, J. F. Ormes, V. S. Paliya, Z. Pei, H. Peña-Herazo, M. Persic, M. Pesce-Rollins, L. Petrov, F. Piron, H. Poon, G. Principe, S. Raino', R. Rando, B. Rani, M. Razzano, S. Razzaque, A. Reimer, O. Reimer, F. K. Schinzel, D. Serini, C. Sgro', E. J. Siskind, G. Spandre, P. Spinelli, D. J. Suson, Y. Tachibana, D. J. Thompson, D. F. Torres, E. Torresi, E. Troja, J. Valverde, P. van Zyl, and M. Yassine

Subjects
Astrophysics
Abstract

The fourth catalog of active galactic nuclei (AGNs) detected by the Fermi Gamma-ray Space Telescope Large Area Telescope (4LAC) between 2008 August 4 and 2016 August 2 contains $2863$ objects located at high Galactic latitudes (|b|>10°). It includes 85% more sources than the previous 3LAC catalog based on 4 yr of data. AGNs represent at least 79% of the high-latitude sources in the fourth Fermi-Large Area Telescope Source Catalog (4FGL), which covers the energy range from 50 MeV to 1 TeV. In addition, 344 gamma-ray AGNs are found at low Galactic latitudes. Most of the 4LAC AGNs are blazars (98%), while the remainder are other types of AGNs. The blazar population consists of 24% Flat Spectrum Radio Quasars (FSRQs), 38% BL Lac-type objects, and 38% blazar candidates of unknown types (BCUs). On average, FSRQs display softer spectra and stronger variability in the gamma-ray band than BL Lacs do, confirming previous findings. All AGNs detected by ground-based atmospheric Cerenkov telescopes are also found in the 4LAC.

Published
2020
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3. Fermi Large Area Telescope Fourth Source Catalog

Author

S. Abdollahi, F. Acero, M. Ackermann, M. Ajello, W. B. Atwood, M. Axelsson, L. Baldini, J. Ballet, G. Barbiellini, D. Bastieri, J. Becerra Gonzalez, R. Bellazzini, A. Berretta, E. Bissaldi, R. D. Blandford, E. D. Bloom, R. Bonino, E. Bottacini, T. J. Brandt, J. Bregeon, P. Bruel, R. Buehler, T. H. Burnett, S. Buson, R. A. Cameron, R. Caputo, P. A. Caraveo, J. M. Casandjian, D. Castro, E. Cavazzuti, E. Charles, S. Chaty, S. Chen, C. C. Cheung, G. Chiaro, S. Ciprini, J. Cohen-Tanugi, L. R. Cominsky, J. Coronado-Blázquez, D. Costantin, A. Cuoco, S. Cutini, F. D'Ammando, M. DeKlotz, P. de la Torre Luque, F. de Palma, A. Desai, S. W. Digel, N. Di Lalla, M. Di Mauro, L. Di Venere, A. Dominguez, D. Dumora, F. Fana Dirirsa, S. J. Fegan, E. C. Ferrara, A. Franckowiak, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, D. Gasparrini, N. Giglietto, P. Giommi, F. Giordano, M. Giroletti, T. Glanzman, D. Green, I. A. Grenier, S. Griffin, M.-H. Grondin, J. E. Grove, S. Guiriec, A. K. Harding, K. Hayashi, E. Hays, J. W. Hewitt, D. Horan, G. Jóhannesson, T. J. Johnson, T. Kamae, M. Kerr, D. Kocevski, M. Kovac’evic’, M. Kuss, D. Landriu, S. Larsson, L. Latronico, M. Lemoine-Goumard, J. Li, I. Liodakis, F. Longo, F. Loparco, B. Lott, M. N. Lovellette, P. Lubrano, G. M. Madejski, S. Maldera, D. Malyshev, A. Manfreda, E. J. Marchesini, L. Marcotulli, G. Martí-Devesa, P. Martin, F. Massaro, M. N. Mazziotta, J. E. McEnery, I. Mereu, M. Meyer, P. F. Michelson, N. Mirabal, T. Mizuno, M. E. Monzani, A. Morselli, I. V. Moskalenko, M. Negro, E. Nuss, R. Ojha, N. Omodei, M. Orienti, E. Orlando, J. F. Ormes, M. Palatiello, V. S. Paliya, D. Paneque, Z. Pei, H. Peña-Herazo, J. S. Perkins, M. Persic, M. Pesce-Rollins, V. Petrosian, L. Petrov, F. Piron, H. Poon, T. A. Porter, G. Principe, S. Raino', R. Rando, M. Razzano, S. Razzaque, A. Reimer, O. Reimer, Q. Remy, T. Reposeur, R. W. Romani, P. M. Saz Parkinson, F. K. Schinzel, D. Serini, C. Sgro', E. J. Siskind, D. A. Smith, G. Spandre, P. Spinelli, A. W. Strong, D. J. Suson, H. Tajima, M. N. Takahashi, D. Tak, J. B. Thayer, D. J. Thompson, L. Tibaldo, D. F. Torres, E. Torresi, J. Valverde, B. Van Klaveren, P. van Zyl, K. Wood, M. Yassine, and G. Zaharijas

Subjects
Astrophysics
Abstract

We present the fourth Fermi Large Area Telescope catalog (4FGL) of gamma-ray sources. Based on the first eight years of science data from the Fermi Gamma-ray Space Telescope mission in the energy range from 50 MeV to 1 TeV, it is the deepest yet in this energy range. Relative to the 3FGL catalog, the 4FGL catalog has twice as much exposure as well as a number of analysis improvements, including an updated model for the Galactic diffuse gamma-ray emission, and two sets of light curves (one-year and two-month intervals). The 4FGL catalog includes 5064 sources above 4 sigma significance, for which we provide localization and spectral properties. Seventy-five sources are modeled explicitly as spatially extended, and overall, 358 sources are considered as identified based on angular extent, periodicity, or correlated variability observed at other wavelengths. For 1336 sources, we have not found plausible counterparts at other wavelengths. More than 3130 of the identified or associated sources are active galaxies of the blazar class, and 239 are pulsars.

Published
2020
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4. Gamma-ray emission in radio galaxies under the VLBI scope -- II. The relationship between gamma-ray emission and parsec-scale jets in radio galaxies

Author

H. Hase, Bryce Carpenter, Michael Dutka, Tim Natusch, P. R. Burd, Shigeki Horiuchi, Eduardo Ros, J. F. H. Quick, Matthias Kadler, J. A. Zensus, Jamie Stevens, Cornelia Müller, Sergei Gulyaev, F. Rösch, James E. J. Lovell, J. Wilms, Anastasios Tzioumis, R. Angioni, R. Ojha, Stuart Weston, Felicia Krauß, Christian Plötz, Robert Schulz, P. G. Edwards, and Chris Phillips

Subjects
Astronomy, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Library science, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, 0103 physical sciences, Very-long-baseline interferometry, media_common.cataloged_instance, European union, Space research, Aerospace, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Commonwealth government, media_common, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, business.industry, Vega, Astronomy and Astrophysics, Radio astronomy observatory, Space and Planetary Science, Commonwealth, business, Astrophysics - High Energy Astrophysical Phenomena
Abstract

Following our study of the radio and high-energy properties of $\gamma$-ray-emitting radio galaxies, here we investigate the kinematic and spectral properties of the parsec-scale jets of radio galaxies that have not yet been detected by Fermi-LAT. We take advantage of the regular VLBI observations provided by the TANAMI monitoring program, and explore the kinematic properties of six $\gamma$-ray-faint radio galaxies. We include publicly available VLBI kinematics of $\gamma$-ray-quiet radio galaxies monitored by the MOJAVE program and perform a Fermi-LAT analysis, deriving upper limits. We combine these results with those from our previous paper to construct the largest sample of radio galaxies with combined VLBI and $\gamma$-ray measurements to date. We find superluminal motion up to $\beta_\mathrm{app}=3.6$ in the jet of PKS 2153$-$69. We find a clear trend of higher apparent speed as a function of distance from the jet core on scales of $\sim10^5\,R_s$, corresponding to the end of the collimation and acceleration zone in nearby radio galaxies. We find evidence of subluminal apparent motion in the jets of PKS 1258$-$321 and IC 4296, and no measurable motion for PKS 1549$-$79, PKS 1733$-$565 and PKS 2027$-$308. We compare the VLBI properties of $\gamma$-ray-detected and undetected radio galaxies, and find significantly different distributions of median core flux density, and, possibly, of median core brightness temperature. We find a significant correlation between median core flux density and $\gamma$-ray flux, but no correlation with typical Doppler boosting indicators such as median core brightness temperature and core dominance. Our study suggests that high-energy emission from radio galaxies is related to parsec-scale radio emission from the inner jet, but is not driven by Doppler boosting effects, in contrast to the situation in their blazar counterparts., Comment: Main text: 15 pages, 12 figures, 6 tables. Appendix: 14 pages, 20 figures, 13 tables. Accepted for publication in Astronomy and Astrophysics

Published
2020

5. Tanami Blazars in the IceCube Pev Neutrino Fields

Author

F Krauãÿ, M Kadler, K Mannheim, R Schulz, J Truestedt, J Wilms, R Ojha, E Ros, G Anton, W Baumgartner, T Beuchert, J Blanchard, C Burkel, B Carpenter, T Eberl, P G Edwards, D Eisenacher, D Elsasser, K Fehn, U Fritsch, N Gehrels, C Grafe, C Großberger, H Hase, S Horiuchi, C James, A Kappes, U Katz, A Kreikenbohm, I Kreykenbohm, M Langejahn, K Leiter, E Litzinger, J E J Lovell, C Muller, C Phillips, C Plotz, J Quick, T Steinbring, J Stevens, D J Thompson, and A K Tzioumis

Subjects
Astrophysics
Abstract

The IceCube Collaboration has announced the discovery of a neutrino flux in excess of the atmospheric background. Owing to the steeply falling atmospheric background spectrum, events at PeV energies most likely have an extraterrestrial origin. We present the multiwavelength properties of the six radio-brightest blazars that are positionally coincident with these events using contemporaneous data of the TANAMI blazar sample, including high-resolution images and spectral energy distributions. Assuming the X-ray to γ-ray emission originates in the photoproduction of pions by accelerated protons, the integrated predicted neutrino luminosity of these sources is high enough to explain the two detected PeV events.

Published
2014
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6. Fermi Large Area Telescope Fourth Source Catalog

Author

S. Abdollahi, F. Acero, M. Ackermann, M. Ajello, W. B. Atwood, M. Axelsson, L. Baldini, J. Ballet, G. Barbiellini, D. Bastieri, J. Becerra Gonzalez, R. Bellazzini, A. Berretta, E. Bissaldi, R. D. Blandford, E. D. Bloom, R. Bonino, E. Bottacini, T. J. Brandt, J. Bregeon, P. Bruel, R. Buehler, T. H. Burnett, S. Buson, R. A. Cameron, R. Caputo, P. A. Caraveo, J. M. Casandjian, D. Castro, E. Cavazzuti, E. Charles, S. Chaty, S. Chen, C. C. Cheung, G. Chiaro, S. Ciprini, J. Cohen-Tanugi, L. R. Cominsky, J. Coronado-Blázquez, D. Costantin, A. Cuoco, S. Cutini, F. D’Ammando, M. DeKlotz, P. de la Torre Luque, F. de Palma, A. Desai, S. W. Digel, N. Di Lalla, M. Di Mauro, L. Di Venere, A. Domínguez, D. Dumora, F. Fana Dirirsa, S. J. Fegan, E. C. Ferrara, A. Franckowiak, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, D. Gasparrini, N. Giglietto, P. Giommi, F. Giordano, M. Giroletti, T. Glanzman, D. Green, I. A. Grenier, S. Griffin, M.-H. Grondin, J. E. Grove, S. Guiriec, A. K. Harding, K. Hayashi, E. Hays, J. W. Hewitt, D. Horan, G. Jóhannesson, T. J. Johnson, T. Kamae, M. Kerr, D. Kocevski, M. Kovac’evic’, M. Kuss, D. Landriu, S. Larsson, L. Latronico, M. Lemoine-Goumard, J. Li, I. Liodakis, F. Longo, F. Loparco, B. Lott, M. N. Lovellette, P. Lubrano, G. M. Madejski, S. Maldera, D. Malyshev, A. Manfreda, E. J. Marchesini, L. Marcotulli, G. Martí-Devesa, P. Martin, F. Massaro, M. N. Mazziotta, J. E. McEnery, I. Mereu, M. Meyer, P. F. Michelson, N. Mirabal, T. Mizuno, M. E. Monzani, A. Morselli, I. V. Moskalenko, M. Negro, E. Nuss, R. Ojha, N. Omodei, M. Orienti, E. Orlando, J. F. Ormes, M. Palatiello, V. S. Paliya, D. Paneque, Z. Pei, H. Peña-Herazo, J. S. Perkins, M. Persic, M. Pesce-Rollins, V. Petrosian, L. Petrov, F. Piron, H. Poon, T. A. Porter, G. Principe, S. Rainò, R. Rando, M. Razzano, S. Razzaque, A. Reimer, O. Reimer, Q. Remy, T. Reposeur, R. W. Romani, P. M. Saz Parkinson, F. K. Schinzel, D. Serini, C. Sgrò, E. J. Siskind, D. A. Smith, G. Spandre, P. Spinelli, A. W. Strong, D. J. Suson, H. Tajima, M. N. Takahashi, D. Tak, J. B. Thayer, D. J. Thompson, L. Tibaldo, D. F. Torres, E. Torresi, J. Valverde, B. Van Klaveren, P. van Zyl, K. Wood, M. Yassine, G. Zaharijas, 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 Univers et Particules de Montpellier (LUPM), 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), 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), 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), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Fermi-LAT, Abdollahi, S., Acero, F., Ackermann, M., Ajello, M., Atwood, W. B., Axelsson, M., Baldini, L., Ballet, J., Barbiellini, G., Bastieri, D., Becerra Gonzalez, J., Bellazzini, R., Berretta, A., Bissaldi, E., Blandford, R. D., Bloom, E. D., Bonino, R., Bottacini, E., Brandt, T. J., Bregeon, J., Bruel, P., Buehler, R., Burnett, T. H., Buson, S., Cameron, R. A., Caputo, R., Caraveo, P. A., Casandjian, J. M., Castro, D., Cavazzuti, E., Charles, E., Chaty, S., Chen, S., Cheung, C. C., Chiaro, G., Ciprini, S., Cohen-Tanugi, J., Cominsky, L. R., Coronado-Blazquez, J., Costantin, D., Cuoco, A., Cutini, S., D'Ammando, F., Deklotz, M., Torre Luque, P. D. L., De Palma, F., Desai, A., Digel, S. W., Lalla, N. D., Mauro, M. D., Venere, L. D., Dominguez, A., Dumora, D., Dirirsa, F. F., Fegan, S. J., Ferrara, E. C., Franckowiak, A., Fukazawa, Y., Funk, S., Fusco, P., Gargano, F., Gasparrini, D., Giglietto, N., Giommi, P., Giordano, F., Giroletti, M., Glanzman, T., Green, D., Grenier, I. A., Griffin, S., Grondin, M. -H., Grove, J. E., Guiriec, S., Harding, A. K., Hayashi, K., Hays, E., Hewitt, J. W., Horan, D., Johannesson, G., Johnson, T. J., Kamae, T., Kerr, M., Kocevski, D., Kovac'Evic', M., Kuss, M., Landriu, D., Larsson, S., Latronico, L., Lemoine-Goumard, M., Li, J., Liodakis, I., Longo, F., Loparco, F., Lott, B., Lovellette, M. N., Lubrano, P., Madejski, G. M., Maldera, S., Malyshev, D., Manfreda, A., Marchesini, E. J., Marcotulli, L., Marti-Devesa, G., Martin, P., Massaro, F., Mazziotta, M. N., Mcenery, J. E., Mereu, I., Meyer, M., Michelson, P. F., Mirabal, N., Mizuno, T., Monzani, M. E., Morselli, A., Moskalenko, I. V., Negro, M., Nuss, E., Ojha, R., Omodei, N., Orienti, M., Orlando, E., Ormes, J. F., Palatiello, M., Paliya, V. S., Paneque, D., Pei, Z., Peña-Herazo, H., Perkins, J. S., Persic, M., Pesce-Rollins, M., Petrosian, V., Petrov, L., Piron, F., Poon, H., Porter, T. A., Principe, G., Rain, S., Rando, R., Razzano, M., Razzaque, S., Reimer, A., Reimer, O., Remy, Q., Reposeur, T., Romani, R. W., Parkinson, P. M. S., Schinzel, F. K., Serini, D., Sgr, C., Siskind, E. J., Smith, D. A., Spandre, G., Spinelli, P., Strong, A. W., Suson, D. J., Tajima, H., Takahashi, M. N., Tak, D., Thayer, J. B., Thompson, D. J., Tibaldo, L., Torres, D. F., Torresi, E., Valverde, J., Klaveren, B. V., Zyl, P. V., Wood, K., Yassine, M., Zaharijas, G., National Aeronautics and Space Administration (US), Department of Energy (US), Commissariat à l'Ènergie Atomique et aux Ènergies Alternatives (France), Centre National de la Recherche Scientifique (France), Institut National de Physique Nucléaire et de Physique des Particules (France), Agenzia Spaziale Italiana, Istituto Nazionale di Fisica Nucleare, Ministry of Education, Culture, Sports, Science and Technology (Japan), High Energy Accelerator Research Organization (Japan), Japan Aerospace Exploration Agency, Knut and Alice Wallenberg Foundation, Swedish Research Council, Swedish National Space Board, Istituto Nazionale di Astrofisica, 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), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Montpellier 2 - Sciences et Techniques (UM2), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), 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 (UMR7158 / UMR_E_9005 / UM_112)), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-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), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Sky surveys, 7. Clean energy, 01 natural sciences, law.invention, Telescope, law, 0103 physical sciences, Range (statistics), 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, Gamma-ray astronomy, 010308 nuclear & particles physics, Detection threshold, Astrophysics::Instrumentation and Methods for Astrophysics, Spectral density, Astronomy and Astrophysics, Light curve, Catalogues, Space and Planetary Science, Catalogs, ddc:520, Catalog, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Data release, Energy (signal processing), Fermi Gamma-ray Space Telescope
Abstract

We present the fourth Fermi Large Area Telescope catalog (4FGL) of γ-ray sources. Based on the first eight years of science data from the Fermi Gamma-ray Space Telescope mission in the energy range from 50 MeV to 1 TeV, it is the deepest yet in this energy range. Relative to the 3FGL catalog, the 4FGL catalog has twice as much exposure as well as a number of analysis improvements, including an updated model for the Galactic diffuse γ-ray emission, and two sets of light curves (one-year and two-month intervals). The 4FGL catalog includes 5064 sources above 4σ significance, for which we provide localization and spectral properties. Seventy-five sources are modeled explicitly as spatially extended, and overall, 358 sources are considered as identified based on angular extent, periodicity, or correlated variability observed at other wavelengths. For 1336 sources, we have not found plausible counterparts at other wavelengths. More than 3130 of the identified or associated sources are active galaxies of the blazar class, and 239 are pulsars., The Fermi LAT Collaboration acknowledges generous ongoing support from a number of agencies and institutes that have supported both the development and the operation of the LAT as well as scientific data analysis. These include the National Aeronautics and Space Administration and the Department of Energy in the United States, the Commissariat à l’Energie Atomique and the Centre National de la Recherche Scientifique/Institut National de Physique Nucléaire et de Physique des Particules in France, the Agenzia Spaziale Italiana and the Istituto Nazionale di Fisica Nucleare in Italy, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), High Energy Accelerator Research Organization (KEK) and Japan Aerospace Exploration Agency (JAXA) in Japan, and the K. A. Wallenberg Foundation, the Swedish Research Council and the Swedish National Space Board in Sweden. Additional support for scientific analysis during the operations phase is gratefully acknowledged from the Istituto Nazionale di Astrofisica in Italy and the Centre National d’Études Spatiales in France. This work performed in part under DOE Contract DE-AC02-76SF00515 and MIUR contract FIRB-2012-RBFR12PM1F. This work made extensive use of the ATNF pulsar catalog104 (Manchester et al. 2005). This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration, and of archival data, software and online services provided by the ASI Science Data Center (ASDC) operated by the Italian Space Agency. We used the Manitoba SNR catalog (Ferrand & Safi-Harb 2012) to check recently published extended sources.

Published
2020
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7. Detection of the blazar S4 0954+65 at very-high-energy with the MAGIC telescopes during an exceptionally high optical state

Author

M. Hayashida, Satoshi Masuda, Arka Chatterjee, Juan Abel Barrio, D. Fidalgo, Yu. V. Troitskaya, Svetlana G. Jorstad, Emilia Järvelä, Marc Ribó, J. A. Acosta Pulido, Wrijupan Bhattacharyya, L. Maraschi, Kari Nilsson, P. Bangale, Hidetoshi Kubo, J. Hose, Stefano Ansoldi, Yusuke Konno, D. Elsaesser, Riccardo Paoletti, Tomislav Terzić, Francesco Longo, Elina Lindfors, P. G. Prada Moroni, Daniel Mazin, G. A. Borman, Alessandro Carosi, V. Fallah Ramazani, J. Palacio, D. Ninci, Kazuma Ishio, Pratik Majumdar, A. Berti, J. M. Paredes, Antonio Stamerra, N. Torres-Albà, J. Kushida, M. V. Fonseca, Jose Luis Contreras, M. Peresano, M. Makariev, G. Bonnoli, D. Kuveždić, Tarek M. Hassan, W. Bednarek, G. Pedaletti, Juan Cortina, Fabrizio Tavecchio, Martin Will, Chiara Righi, R. Ch. Berse, Ll. Font, Razmik Mirzoyan, Rodolfo Carosi, Dario Hrupec, Jose Miguel Miranda, J. Becerra González, M. A. Lopez, J. R. Garcia, Marina Manganaro, U. Barres de Almeida, P. Temnikov, E. Colombo, Oscar Blanch, T. S. Grishina, Mitsunari Takahashi, Stefano Covino, Louis Antonelli, Damir Lelas, Valeri M. Larionov, Aaron Dominguez, D. Galindo, Merja Tornikoski, Sergey S. Savchenko, Francesco Dazzi, Manuel Delfino, D. Dominis Prester, Wolfgang Rhode, Nikola Godinovic, Shimpei Tsujimoto, Tomoki Saito, Giovanni Ceribella, A. A. Vasilyev, Ana Babić, P. Cumani, L. O. Takalo, Konstancja Satalecka, L. Nogués, Michele Doro, Max Ludwig Ahnen, Dorota Sobczyńska, R. Ojha, K. Mielke, J. Finke, E. Moretti, Ievgen Vovk, P. Giammaria, Jordi Delgado, F. Di Pierro, Camilla Maggio, Daniela Dorner, Dariusz Gora, M. Gaug, G. Vanzo, C. Protasio, J. Herrera, D. Hadasch, Alba Fernández-Barral, Carolina Casadio, Anne Lähteenmäki, Mosè Mariotti, Masahiro Teshima, Alexander Hahn, E. Prandini, Cosimo Nigro, M. Nievas Rosillo, T. Nagayoshi, Kyoshi Nishijima, M. Minev, Iva Šnidarić, T. Schweizer, J. E. Ward, Sidika Merve Colak, E. N. Kopatskaya, A. Niedzwiecki, Koji Noda, Elisa Bernardini, Ivan S. Troitsky, David Paneque, D. Guberman, Saverio Lombardi, Andrea Rugliancich, V. Ramakrishnan, M. I. Martínez, Sabrina Einecke, Ivica Puljak, Pierre Colin, Markus Garczarczyk, M. I. Carnerero, Talvikki Hovatta, Sol N. Molina, P. Da Vela, Julian Sitarek, S. Paiano, Karl Mannheim, D. A. Morozova, A. De Angelis, A. Treves, Vitaly Neustroev, M. Vazquez Acosta, L. V. Larionova, G. Maneva, I. Agudo, Adrian Biland, Tihomir Surić, J. Rico, Dominik Baack, Alan P. Marscher, Christian Fruck, Victoria Moreno, Darko Zarić, B. De Lotto, Abelardo Moralejo, I. Reichardt, Mark Gurwell, B. Banerjee, Marcel Strzys, C. Arcaro, R. J. García López, Massimo Persic, Yasuyuki T. Tanaka, Ahnen, M. L., Ansoldi, S., Antonelli, L. A., Arcaro, C., Baack, D., Babić, A., Banerjee, B., Bangale, P., Barres De Almeida, U., Barrio, J. A., Bednarek, W., Bernardini, E., Berse, R. Ch., Berti, A., Bhattacharyya, W., Biland, A., Blanch, O., Bonnoli, G., Carosi, R., Carosi, A., 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., Domínguez, A., Dominis Prester, D., Dorner, D., Doro, M., Einecke, S., Elsaesser, D., Fallah Ramazani, V., Fernández-Barral, A., Fidalgo, D., Fonseca, M. V., Font, L., Fruck, C., Galindo, D., García López, R. J., 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., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Masuda, S., Mazin, D., Mielke, K., Minev, M., Miranda, J. M., Mirzoyan, R., Moralejo, A., Moreno, V., Moretti, E., Nagayoshi, T., Neustroev, V., Niedzwiecki, A., Nievas Rosillo, M., 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., Persic, M., Prada Moroni, P. G., Prandini, E., Puljak, I., Garcia, J. R., Reichardt, I., Rhode, W., Ribó, M., Rico, J., Righi, C., Rugliancich, A., Saito, T., Satalecka, K., Schweizer, T., Sitarek, J., Šnidarić, I., Sobczynska, D., Stamerra, A., Strzys, M., Surić, T., Takahashi, M., Takalo, L., Tavecchio, F., Temnikov, P., Terzić, T., Teshima, M., Torres-Albà, N., Treves, A., Tsujimoto, S., Vanzo, G., Vazquez Acosta, M., Vovk, I., Ward, J. E., Will, M., Zarić, D., Becerra González, J., Tanaka, Y., Ojha, R., Finke, J., Lähteenmäki, A., Järvelä, E., Tornikoski, M., Ramakrishnan, V., Hovatta, T., Jorstad, S. G., Marscher, A. P., Larionov, V. M., Borman, G. A., Grishina, T. S., Kopatskaya, E. N., Larionova, L. V., Morozova, D. A., Savchenko, S. S., Troitskaya, Yu. V., Troitsky, I. S., Vasilyev, A. A., Agudo, I., Molina, S. N., Casadio, C., Gurwell, M., Carnerero, M. I., Protasio, C., Acosta Pulido, J. A., Ministerio de Economía y Competitividad (España), Swiss National Science Foundation, Federal Ministry of Education and Research (Germany), Junta de Andalucía, Max Planck Society, Universitat de Barcelona, Department of Electronics and Nanoengineering, Aalto-yliopisto, and Aalto University

Subjects
individual: S4 0954+65 [BL Lacertae objects], Active galactic nucleus, active [Galaxies], BL Lacertae objects: individual: S4 0954+65, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Galaxies: active, Gamma rays: galaxies, Astronomy and Astrophysics, Space and Planetary Science, 0103 physical sciences, Gamma ray astronomy, Astronomia de raigs gamma, gamma rays:galaxies, galaxies:active, BL Lacertae objects:individual:S40954+65, Blazar, 010303 astronomy & astrophysics, Quasars, Astrophysics::Galaxy Astrophysics, Quàsars, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, gamma rays: galaxies, galaxies: active, galaxie [Gamma rays], 010308 nuclear & particles physics, Compton scattering, Optical polarization, Quasar, Astronomy and Astrophysic, Galaxies, Redshift, Galàxies, galaxies [gamma rays], ddc:520, Spectral energy distribution, Física nuclear, Astrophysics - High Energy Astrophysical Phenomena, Radio wave
Abstract

The very high energy (VHE ¿ 100 GeV) -ray MAGIC observations of the blazar S4 0954+65, were triggered by an exceptionally high flux state of emission in the optical. This blazar has a disputed redshift of z = 0.368 or z ¿ 0.45 and an uncertain classification among blazar subclasses. The exceptional source state described here makes for an excellent opportunity to understand physical processes in the jet of S4 0954+65 and thus contribute to its classification. Methods. We investigated the multiwavelength (MWL) light curve and spectral energy distribution (SED) of the S4 0954+65 blazar during an enhanced state in February 2015 and have put it in context with possible emission scenarios. We collected photometric data in radio, optical, X-ray, and ¿-ray. We studied both the optical polarization and the inner parsec-scale jet behavior with 43 GHz data. Results. Observations with the MAGIC telescopes led to the first detection of S4 0954+65 at VHE. Simultaneous data with Fermi-LAT at high energy ¿-ray(HE, 100 MeV < E < 100 GeV) also show a period of increased activity. Imaging at 43 GHz reveals the emergence of a new feature in the radio jet in coincidence with the VHE flare. Simultaneous monitoring of the optical polarization angle reveals a rotation of approximately 100. Conclusions. The high emission state during the flare allows us to compile the simultaneous broadband SED and to characterize it in the scope of blazar jet emission models. The broadband spectrum can be modeled with an emission mechanism commonly invoked for flat spectrum radio quasars (FSRQs), that is, inverse Compton scattering on an external soft photon field from the dust torus, also known as external Compton. The light curve and SED phenomenology is consistent with an interpretation of a blob propagating through a helical structured magnetic field and eventually crossing a standing shock in the jet, a scenario typically applied to FSRQs and low-frequency peaked BL Lac objects (LBL). © ESO 2018., 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, CSD2009-00064), and the Japanese JSPS and MEXT is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia “Severo Ochoa” SEV-2012-0234 and SEV-2015-0548, and Unidad de Excelencia “María de Maeztu” MDM-2014-0369, by the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782 and the University of Rijeka Project 13.12.1.3.02, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, the Polish National Research Centre grant UMO-2016/22/M/ST9/00382 and by the Brazilian MCTIC, CNPq, and FAPERJ. IA acknowledges support by a Ramón y Cajal grant of the Ministerio de Economía, Industria y Competitividad (MINECO) of Spain. The research at the IAA–CSIC was supported in part by the MINECO through grants AYA2016–80889–P, AYA2013–40825–P, and AYA2010–14844, and by the regional government of Andalucía through grant P09–FQM–4784.

Published
2018
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8. Gamma-ray Beacons at the Dawn of the Universe

Author

R. Ojha, D. Gasparrini, Marco Ajello, and Vaidehi S. Paliya

Subjects
Physics, Supermassive black hole, Astrophysics::High Energy Astrophysical Phenomena, media_common.quotation_subject, Gamma ray, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Universe, Accretion disc, Emission spectrum, Blazar, Spectroscopy, Astrophysics::Galaxy Astrophysics, media_common
Abstract

Gamma ray detected high-redshift blazars (z>3) are intrinsically interesting since they inform us about the evolution of gamma-ray blazars and are, by definition, some of the more luminous blazars in the Universe. It has been found in many studies that such high z blazars host extremely massive black holes ($M_{\rm BH}> 10^{9} {M_{\odot}}$) and thus shed a new light on the formation of supermassive black holes in the early Universe. Here we report the first detection of gamma-ray emitting blazars beyond z=3.1 using the sensitive Pass 8 dataset of Fermi-LAT. These objects are found to host extremely massive black holes at their centers, as confirmed from both IR-UV continuum modelling with a standard accretion disk and also with the emission line measurements using optical spectroscopy. Further details of the results will be presented within the framework of the disk-jet connection in powerful jetted AGNs.

Published
2017
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9. The first VHE detection of the blazar S4 0954+65 with the MAGIC telescopes during an exceptionally high optical state

Author

G. A. Borman, Talvikki Hovatta, M. Doert, Anne Lähteenmäki, J. Becerra González, Marina Manganaro, Merja Tornikoski, Valeri M. Larionov, J. Finke, Alan P. Marscher, Elina Lindfors, G. Pedaletti, I. S. Troitsky, V. Fallah Ramazani, M. Nievas Rosillo, S. G. Jorstad, Yasuyuki T. Tanaka, and R. Ojha

Subjects
Physics, ta115, Astrophysics::High Energy Astrophysical Phenomena, Gamma ray, Flux, Astronomy, Astrophysics, Redshift, law.invention, Crab Nebula, law, MAGIC (telescope), Blazar, Flare, Fermi Gamma-ray Space Telescope
Abstract

The blazar S4 0954+65 (at a disputed redshift of z=0.368 or z≥0.45) underwent an exceptionally high state in the optical band during January and February 2015, as revealed by the Tuorla and St. Petersburg University blazar monitoring programs: a brightening of more than 3 magnitudes in the R-band from the average monitored states. Simultaneous data from the Fermi satellite at high energy gamma rays (HE, 100 MeV 100 GeV) emission from S4 0954+65 (ATel #7080). The VHE flux above 150 GeV is estimated to be about 6% of the Crab nebula flux above the same threshold.In this contribution we present a comprehensive multiwavelength picture of this object, including data from mm/optical/X-ray/HE and VHE gamma-ray bands. The high emission state during the flare allows us to compile the simultaneous broadband spectral energy distribu...

Published
2017
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10. The MHz-peaked radio spectrum of the unusual γ-ray source PMN J1603-4904

Author

R. Ojha, Matthias Kadler, P. R. Burd, Hubertus Intema, Heino Falcke, R. Coppejans, C. Müller, Robert Schulz, Felicia Krauß, and High Energy Astrophys. & Astropart. Phys (API, FNWI)

Subjects
Radio galaxy, media_common.quotation_subject, Astronomy, Astrophysics::High Energy Astrophysical Phenomena, Population, FOS: Physical sciences, Context (language use), Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Radio spectrum, 0103 physical sciences, Blazar, education, 010303 astronomy & astrophysics, GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries), Astrophysics::Galaxy Astrophysics, media_common, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Giant Metrewave Radio Telescope, education.field_of_study, 010308 nuclear & particles physics, Astronomy and Astrophysics, Space and Planetary Science, Sky, Astrophysics - High Energy Astrophysical Phenomena, Fermi Gamma-ray Space Telescope
Abstract

Context. The majority of bright extragalactic gamma-ray sources are blazars. Only a few radio galaxies have been detected by Fermi/LAT. Recently, the GHz-peaked spectrum source PKS 1718-649 was confirmed to be gamma-ray bright, providing further evidence for the existence of a population of gamma-ray loud, compact radio galaxies. A spectral turnover in the radio spectrum in the MHz to GHz range is a characteristic feature of these objects, which are thought to be young due to their small linear sizes. The multiwavelength properties of the gamma-ray source PMN J1603-4904 suggest that it is a member of this source class. Aims. The known radio spectrum of PMN J1603-4904 can be described by a power law above 1 GHz. Using observations from the Giant Metrewave Radio Telescope (GMRT) at 150, 325, and 610 MHz, we investigate the behaviour of the spectrum at lower frequencies to search for a low-frequency turnover. Methods. Data from the TIFR GMRT Sky Survey (TGSS ADR) catalogue and archival GMRT observations were used to construct the first MHz to GHz spectrum of PMN J1603-4904. Results. We detect a low-frequency turnover of the spectrum and measure the peak position at about 490 MHz (rest-frame), which, using the known relation of peak frequency and linear size, translates into a maximum linear source size of ~1.4 kpc. Conclusions. The detection of the MHz peak indicates that PMN J1603-4904 is part of this population of radio galaxies with turnover frequencies in the MHz to GHz regime. Therefore it can be considered the second, confirmed object of this kind detected in gamma-rays. Establishing this gamma-ray source class will help to investigate the gamma-ray production sites and to test broadband emission models., Comment: 5 pages, A&A (Letters) accepted

Published
2016
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11. MODELING X–RAY EMISSION OF A STRAIGHT JET: PKS 0920-397

Author

Leith Godfrey, Svetlana G. Jorstad, Diana M Worrall, Geoffrey V. Bicknell, Martin J. Hardcastle, Daniel A. Evans, A. Siemiginowska, Sebastian Jester, Francesco Massaro, R. Ojha, Eric S. Perlman, Mark Birkinshaw, Lukasz Stawarz, H. L. Marshall, Jonathan Gelbord, James E. J. Lovell, and D. A. Schwartz

Subjects
Physics, education.field_of_study, Line-of-sight, Scattering, Astrophysics::High Energy Astrophysical Phenomena, Lorentz transformation, Population, Cosmic microwave background, Astronomy and Astrophysics, Quasar, Astrophysics::Cosmology and Extragalactic Astrophysics, Electron, Astrophysics, jet emission mechanisms, symbols.namesake, Lorentz factor, Space and Planetary Science, symbols, Quasar jets, X-ray jets, Mathematical Physics, education, Astrophysics::Galaxy Astrophysics
Abstract

We summarize a study of PKS 0920-397 using our 42 ks Chandra observation in conjunction with our ATCA 20GHz image, and HST/ACS F814W and F475W images. We investigate the hypothesis that the jet X–ray emission is due to inverse-Compton (IC) scattering on the cosmic microwave background (CMB) from the same population of relativistic electrons that give rise to the radio emission. To calculate parameters intrinsic to the source, one must finesse the fact that we do not know the true angle of the jet to our line of sight. Typical assumptions are that the Doppler factor equals the bulk Lorentz factor, or that the Lorentz factor takes some fixed numerical value. While giving useful estimates, neither assumption can be exact in general. We try different constraints to determine the jet quantities. It is plausible that the kinetic flux is constant along the jet, prior to a terminal hotspot or lobe, and with minimal bending of the jet. Alternatively, because PKS 0920-397 appears straight in projection on the sky, we might assume the jet maintains a constant angle to our line of sight. Either approach gives bulk Lorentz factors of 6 to 8, with kinetic energy flux of order 1046 erg s-1, and with the jet at an angle 2° to 4° from our line of sight.

Published
2010
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12. THE ALGOL TRIPLE SYSTEM SPATIALLY RESOLVED AT OPTICAL WAVELENGTHS

Author

Christian A. Hummel, D. J. Hutter, D. B. Shaffer, R. Ojha, Mercedes T. Richards, C. Tycner, D. A. Boboltz, and R. T. Zavala

Subjects
Orbital elements, Physics, 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Binary number, Astronomy and Astrophysics, Astrophysics, Astrometry, Light curve, Position angle, 01 natural sciences, Interferometry, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, 0103 physical sciences, Binary star, Astronomical interferometer, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences
Abstract

Interacting binaries typically have separations in the milli-arcsecond regime and hence it has been challenging to resolve them at any wavelength. However, recent advances in optical interferometry have improved our ability to discern the components in these systems and have now enabled the direct determination of physical parameters. We used the Navy Prototype Optical Interferometer to produce for the first time images resolving all three components in the well-known Algol triple system. Specifically, we have separated the tertiary component from the binary and simultaneously resolved the eclipsing binary pair, which represents the nearest and brightest eclipsing binary in the sky. We present revised orbital elements for the triple system, and we have rectified the 180-degree ambiguity in the position angle of Algol C. Our directly determined magnitude differences and masses for this triple star system are consistent with earlier light curve modeling results., Accepted to Astrophysical Journal Letters, 15 pages, 2 eps figures.

Published
2010
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13. Parsec‐Scale Blazar Monitoring: The Data

Author

John F. C. Wardle, Margo F. Aller, Daniel C. Homan, Philip A. Hughes, David H. Roberts, R. Ojha, and Hugh D. Aller

Subjects
Luminous infrared galaxy, Physics, Proper motion, Radio galaxy, Astrophysics::High Energy Astrophysical Phenomena, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Polarization (waves), Disc galaxy, Data modeling, Space and Planetary Science, Blazar, Circular polarization
Abstract

We present the images and modeling data obtained from a dual frequency, six-epoch, VLBA polarization experiment monitoring a sample of 12 blazars. The observations were made at 15 and 22 GHz at evenly spaced, bimonthly intervals over 1996. The advent of the VLBA makes possible a data set with reliable calibration as well as regular and frequent temporal sampling. Detection of circular polarization, proper motion studies, and flux and polarization variability in the sample are some of the topics that such a data set makes available for robust investigation.

Published
2004
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14. Proper motions, flux and polarization variability from a parsec scale blazar monitoring program

Author

R. Ojha, David H. Roberts, Daniel C. Homan, and John F. C. Wardle

Subjects
Physics, Proper motion, Active galactic nucleus, Astrophysics::High Energy Astrophysical Phenomena, Astronomy, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Polarization (waves), Monitoring program, Magnetic field, Polarization sensitive, Space and Planetary Science, Very-long-baseline interferometry, Blazar, Astrophysics::Galaxy Astrophysics
Abstract

We review the results from a polarization sensitive, six-epoch (at about 2 month intervals), dual frequency (22 and 15 GHz) VLBA program that monitored rapid changes in the structure and polarization of 12 highly active AGN jets. Our analysis of the proper motion, polarization and flux variability of VLBI ‘components’, is in the context of some key questions addressed at this meeting including, dependence of jet velocities on distance from nucleus, structure and evolution of jet magnetic fields and jet morphology.

Published
2003
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15. Erratum: 'The Algol Triple System Spatially Resolved at Optical Wavelengths' (2010, ApJL, 715, L44)

Author

D. A. Boboltz, Christopher Tycner, C. A. Hummel, R. Ojha, D. B. Shaffer, D. J. Hutter, R. T. Zavala, and Mercedes T. Richards

Subjects
Physics, 010504 meteorology & atmospheric sciences, business.industry, Triple system, Spatially resolved, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Wavelength, Optics, Space and Planetary Science, 0103 physical sciences, business, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Published
2017
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16. Electron–positron jets associated with the quasar 3C279

Author

John F. C. Wardle, Daniel C. Homan, R. Ojha, and David H. Roberts

Subjects
Physics, Supermassive black hole, Multidisciplinary, Astrophysics::High Energy Astrophysical Phenomena, Astronomy, Quasar, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Electron, Plasma, Jet (particle physics), Positron, Astrophysical jet, High Energy Physics::Experiment, Astrophysics::Galaxy Astrophysics, Circular polarization
Abstract

A long-standing question in extragalactic astrophysics is the composition of the relativistic jets of plasma that stream from the nuclei of quasars and active galaxies—do they consist of a ‘normal’ (electron–proton) plasma, or a ‘pair’ (electron–positron) plasma? Distinguishing between these possibilities is crucial for understanding the physical processes occurring close to the putative supermassive black holes that are believed responsible for the jets. Here we report the detection of circularly polarized radio emission from the jets of the archtypal quasar 3C279. The circular polarization is produced by Faraday conversion, which requires the energy distribution of the radiating particles to extend to very low energies, indicating that electron–positron pairs are an important component of the jet plasma. Similar detections in three other radio sources suggest that, in general, extragalactic radio jets are composed mainly of an electron–positron plasma.

Published
1998
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17. Enormous disc of cool gas surrounding the nearby powerful radio galaxy NGC 612 (PKS 0131-36)

Author

J. Holt, Raffaella Morganti, R. Ojha, Elaine M. Sadler, J. M. van der Hulst, Clive Tadhunter, Bjorn Emonts, Tom Oosterloo, and Kapteyn Astronomical Institute

Subjects
ISM kinematics and dynamics, GALACTIC NUCLEI, galaxies : evolution, Stellar population, Radio galaxy, galaxies : active, IRAS OBSERVATIONS, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, galaxies : interactions, SURFACE PHOTOMETRY, Luminosity, STELLAR POPULATIONS, SUPERMASSIVE BLACK-HOLES, ELLIPTIC GALAXIES, DARK-MATTER, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Galaxy Astrophysics, STAR-FORMATION THRESHOLDS, Physics, FR-I, NEUTRAL-HYDROGEN, Astrophysics (astro-ph), Astronomy and Astrophysics, Galaxy, Dark matter halo, Barred spiral galaxy, Stars, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, galaxies : individual : NGC 612, Optical disc
Abstract

We present the detection of an enormous disc of cool neutral hydrogen (HI) gas surrounding the S0 galaxy NGC 612, which hosts one of the nearest powerful radio sources (PKS 0131-36). Using the Australia Telescope Compact Array, we detect M_HI = 1.8 x 10^9 M_sun of HI emission-line gas that is distributed in a 140 kpc wide disc-like structure along the optical disc and dust-lane of NGC 612. The bulk of the gas in the disc appears to be settled in regular rotation with a total velocity range of 850 km/s, although asymmetries in this disc indicate that perturbations are being exerted on part of the gas, possibly by a number of nearby companions. The HI disc in NGC 612 suggests that the total mass enclosed by the system is M_enc ~ 2.9 x 10^12 sin^-2(i) M_sun, implying that this early-type galaxy contains a massive dark matter halo. We also discuss an earlier study by Holt et al. that revealed the presence of a prominent young stellar population at various locations throughout the disc of NGC 612, indicating that this is a rare example of an extended radio source that is hosted by a galaxy with a large-scale star-forming disc. In addition, we map a faint HI bridge along a distance of 400 kpc in between NGC 612 and the gas-rich (M_HI = 8.9 x 10^9 M_sun) barred galaxy NGC 619, indicating that likely an interaction between both systems occurred. From the unusual amounts of HI gas and young stars in this early-type galaxy, in combination with the detection of a faint optical shell and the system's high infra-red luminosity, we argue that either ongoing or past galaxy interactions or a major merger event are a likely mechanism for the triggering of the radio source in NGC 612. This paper is part of an ongoing study to map the large-scale neutral hydrogen properties of nearby radio galaxies. --abridged, 13 pages, 9 figures. MNRAS in press. See http://www.blackwell-synergy.com/doi/full/10.1111/j.1365-2966.2008.13142.x for a full resolution version

Published
2008

18. The MASIV Legacy: Surveying AGN Intra-day Variability at Radio Wavelengths

Author

J. P. Macquart, Lucyna Kedziora-Chudczer, James E. J. Lovell, R. Ojha, Jun Yi Koay, C. S. Reynolds, David L. Jauncey, B. J. Rickett, Hayley Bignall, and T. Pursimo

Subjects
Physics, Scintillation, Intra day, Scattering, Astrophysics::High Energy Astrophysical Phenomena, Astronomy, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Galaxy, Interstellar medium, Wavelength, Space and Planetary Science, Radio interferometer, Astrophysics::Galaxy Astrophysics
Abstract

The Micro-arcsecond Scintillation-Induced Variability (MASIV) Survey and its follow-up observations have provided large datasets of AGN intra-day variability (IDV) at radio wavelengths. These data have shown that IDV arises mainly from scintillation caused by scattering in the ionized interstellar medium (ISM) of our Galaxy, based on correlation with Galactic latitudes and line-of-sight Galactic electron column densities. The sensitivity of interstellar scintillation (ISS) towards source angular sizes has provided a new tool for studying the most compact components of radio-loud AGNs at microarcsecond (μas) scale resolution - much higher than any ground-based radio interferometer. We present here key results from the MASIV Survey and its follow-up observations, and point to relevant papers where these results have been published.

Published
2013
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19. Parsec-Scale Blazar Monitoring: Proper Motions

Author

Margo F. Aller, Philip A. Hughes, John F. C. Wardle, Hugh D. Aller, R. Ojha, Daniel C. Homan, and David H. Roberts

Subjects
Physics, Proper motion, Superluminal motion, Astrophysics (astro-ph), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Polarization (waves), Space and Planetary Science, Scale structure, Very-long-baseline interferometry, Dual frequency, Blazar
Abstract

We present proper motions obtained from a dual frequency, six-epoch, VLBA polarization experiment monitoring a sample of 12 blazars. The observations were made at 15 GHz and 22 GHz at bi-monthly intervals over 1996. Ten of the eleven sources for which proper motion could be reliably determined are superluminal. Only J2005+77 has no superluminal components. Three sources (OJ287, J1224+21, and J1512-09) show motion faster than 10h^{-1}c, requiring $\gamma_{pattern}$ of at least 10h^{-1}c (H_0 = 100h km/s/Mpc). We compare our results to those in the literature and find motions outside the previously observed range for four sources. While some jet components exhibit significant non-radial motion, most motion is radial. In at least two sources there are components moving radially at significantly different structural position angles. In five of six sources (3C120, J1224+21, 3C273, 3C279, J1512-09, and J1927+73) that have multiple components with measurable proper motion, the innermost component is significantly slower than the others, suggesting that acceleration occurs in the jet. In the motions of individual components we observe at least one decelerating motion and two ``bending'' accelerations which tend to align their motions with larger scale structure. We also discuss in detail our procedures for obtaining robust kinematical results from multi-frequency VLBI data spanning several epochs., Comment: 27 pages, 37 figures, uses emulateapj5.sty (included), ApJ in Press; very minor revisions to original version

Published
2000

20. Detection of Parsec-Scale Circular Polarization with the VLBA

Author

R. Ojha, David H. Roberts, Daniel C. Homan, and John F. C. Wardle

Subjects
Physics, Polarization rotator, business.industry, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Cosmology and Extragalactic Astrophysics, Plasma, Astrophysics, Electron, Polarization (waves), law.invention, symbols.namesake, Optics, law, Very-long-baseline interferometry, Faraday effect, symbols, business, Faraday rotator, Circular polarization
Abstract

Circular polarization has been detected in 3C 279 and 3C 84 at multiple epochs, using the VLBA at 15 GHz. This is the first detection of circular polarization in a compact radio source at VLBI resolution. In the case of 3C 279 the polarization is most likely produced by the conversion of linear to circular polarization by low energy relativistic electrons in the emitting region. If this is so, the absence of Faraday rotation by the same electrons suggests that the jet consists of an electron-positron plasma.

Published
1998
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21. Evolution of the Parsec-Scale Structures of OJ 287 and 3C 273

Author

D. C. Homan, John F. C. Wardle, David H. Roberts, and R. Ojha

Subjects
Physics, Scale (ratio), Astronomy, Astrophysics, Parsec, BL Lac object
Abstract

We have obtained 15 and 22 GHz linear polarization VLBA images of a sample of strong and rapidly variable polarized sources at six epochs over one year. We observe rapid changes, in both cores and jet components, in total intensity, both with and without associated changes in polarization. Changes in the cores are probably associated with the births of new components. Images of one quasar (3C 273) and one BL Lacertae object (OJ 287) from two epochs are shown here. No significant Faraday rotation is observed at any epoch in any position in either source.

Published
1998
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22. HESS and Fermi-LAT discovery of gamma-rays from the blazar 1ES 1312-423

Author

J. Biteau, Michael Punch, G. Fontaine, Mateusz Janiak, S. J. Fegan, M. Weidinger, Svenja Carrigan, E. Birsin, Gilles Henri, André Schulz, Christian Farnier, G. Lamanna, D. Goering, Dieter Horns, Anna Zajczyk, P. Wagner, K. Dutson, A. Woernlein, Emmanuel Moulin, F. Stinzing, B. Giebels, Alexandre Marcowith, C. L. Naumann, A. A. Zdziarski, M. J. Vorster, A. Jacholkowska, P. Willmann, Michal Dyrda, Thomas Lohse, G. Puehlhofer, T. Garrigoux, Christo Venter, J. Brucker, Gavin Rowell, Dirk Lennarz, R. de los Reyes, Denis Wouters, V. Sahakian, Christoph Deil, Jamie Stevens, M. K. Daniel, Elisabetta Bissaldi, T. Kneiske, J. S. Perkins, S. Haeffner, C. Jahn, U. F. Katz, R. Moderski, A. Zech, Vincent Marandon, D. Klochkov, S. Schwarzburg, H. J. Voelk, P. Espigat, C. Stegmann, Nu. Komin, K. Stycz, F. Schuessler, Tanya Edwards, Luke O'c. Drury, Andreas Quirrenbach, C. Couturier, M. Gajdus, Guillaume Dubus, J. F. Glicenstein, K. Bernloehr, Catherine Boisson, Stefan Ohm, I. Oya, Jacek Niemiec, M. Kieffer, S. Pita, M. Holler, Michael Zacharias, M. Dalton, A. Cheesebrough, Pierre Brun, J. Perez, Philip G. Edwards, Olaf Reimer, S. Schwemmer, Jan Conrad, Matthias Kadler, N. Maxted, Manuel Meyer, J. Dyks, E. de Oña Wilhelmi, A. Reimer, Fabio Acero, Andrea Santangelo, Francois Brun, M. Chrétien, L. Rob, A. Fiasson, D. Fernandez, Matteo Cerruti, M. Panter, M. de Naurois, G. Maurin, Thomas Murach, U. Menzler, F. Krayzel, S. Klepser, Anna Barnacka, B. Khélifi, Roopesh Ojha, G. Hermann, M. A. Kastendieck, Regis Terrier, M. Tluczykont, G. Vasileiadis, M. V. Fernandes, M. Paz Arribas, Francesca Volpe, C. Trichard, M. Fuessling, Werner Hofmann, Michał Ostrowski, P. P. Krueger, F. Feinstein, G. Cologna, C. van Eldik, Jim Hinton, Andreas Hillert, J. D. Hague, M. C. Medina, Y. A. Gallant, H.-S. Zechlin, Felix Jankowsky, Peter Eger, Ullrich Schwanke, C-C Lu, A. Djannati-Ataï, L. Oakes, Henning Gast, M. Renaud, Martin Raue, A. G. Akhperjanian, O. Hervet, R. Steenkamp, I. D. Davids, Iurii Sushch, R. D. Parsons, S. Rosier-Lees, P. deWilt, K. Katarzyński, Marek Jamrozy, M. Mohamed, Helene Sol, J. Harris, Sabrina Casanova, Karl Kosack, Frank M. Rieger, J. Mehault, F. Spiess, S. Raab, A. Abramowski, J.-P. Tavernet, W. Kluzniak, T. J. L. McComb, P-O. Petrucci, B. Peyaud, R. White, S. Colafrancesco, I. Jung, B. Rudak, Kathrin Egberts, P. M. Chadwick, B. Degrange, Marianne Lemoine-Goumard, R. Chalme-Calvet, R. C. G. Chaves, Yvonne Becherini, Anna Szostek, Petter Hofverberg, Aion Viana, B. Opitz, A. Foerster, E. O. Anguener, D. Kolitzus, G. Heinzelmann, J. Bolmont, Guy Pelletier, Alicja Wierzcholska, S. Kaufmann, M. H. Grondin, Helen Poon, A. Lopatin, J.-P. Lenain, Reinhard Schlickeiser, Pol Bordas, Hugh Dickinson, J. Becker Tjus, Daniel Sánchez, M. Grudzińska, N. W. Pekeur, Tomasz Bulik, G. Spengler, S. J. Nolan, Joachim Hahn, W. Domainko, A. Balzer, Stefan Wagner, Gisela Anton, M. Mayer, Cameron B Rulten, S. Balenderan, Felix Aharonian, H. Laffon, K. Valerius, Julien Lefaucheur, D. Nedbal, L. Stawarz, P. Vincent, S. Krakau, Martin Ward, Laboratoire Univers et Particules de Montpellier (LUPM), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Montpellier 2 - Sciences et Techniques (UM2), AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Laboratoire Leprince-Ringuet (LLR), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Pierre et Marie Curie - Paris 6 (UPMC), FERMI, 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)-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), Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), APC - Astrophysique des Hautes Energies (APC - AHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Dipartimento di Astronomia, Universita degli Studi di Bologna, Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), HESS, 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), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-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)-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), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), 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), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Laboratoire d'Annecy de Physique des Particules (LAPP/Laboratoire d'Annecy-le-Vieux de Physique des Particules), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Dipartimento di Astronomia, Universita degli Studi di Bologna, Università di Bologna [Bologna] (UNIBO)-Università di Bologna [Bologna] (UNIBO), 10103449 - Krüger, Petrus Paulus, 22050574 - Pekeur, Nicolette Whilna, 12006653 - Venter, Christo, 12792322 - Vorster, Michael Johannes, 24922986 - Sushch, Iurii, 23909196 - Casanova, Sabrina, A., Abramowski, F., Acero, F., Aharonian, A. G., Akhperjanian, E., Anguener, G., Anton, S., Balenderan, A., Balzer, A., Barnacka, Y., Becherini, J. B., Tju, K., Bernloehr, E., Birsin, Bissaldi, Elisabetta, J., Biteau, C., Boisson, J., Bolmont, P., Borda, J., Brucker, F., Brun, P., Brun, T., Bulik, S., Carrigan, S., Casanova, M., Cerruti, P. M., Chadwick, R., Chalme Calvet, R. C., G., A., Cheesebrough, M., Chretien, S., Colafrancesco, G., Cologna, J., Conrad, C., Couturier, M., Dalton, M. K., Daniel, I. D., David, B., Degrange, C., Deil, P., Dewilt, H. J., Dickinson, A., Djannati Atai, W., Domainko, L. O., '., G., Dubu, K., Dutson, J., Dyk, M., Dyrda, T., Edward, K., Egbert, P., Eger, P., Espigat, C., Farnier, S., Fegan, F., Feinstein, M. V., Fernande, D., Fernandez, A., Fiasson, G., Fontaine, A., Foerster, M., Fuessling, M., Gajdu, Y. A., Gallant, T., Garrigoux, H., Gast, B., Giebel, J. F., Glicenstein, D., Goering, M. . ., H., M., Grudzinska, S., Haeffner, J. D., Hague, J., Hahn, J., Harri, G., Heinzelmann, G., Henri, G., Hermann, O., Hervet, A., Hillert, J. A., Hinton, W., Hofmann, P., Hofverberg, M., Holler, D., Horn, A., Jacholkowska, C., Jahn, M., Jamrozy, M., Janiak, F., Jankowsky, I., Jung, M. A., Kastendieck, K., Katarzynski, U., Katz, S., Kaufmann, B., Khelifi, M., Kieffer, S., Klepser, D., Klochkov, W., Kluzniak, T., Kneiske, D., Kolitzu, N., Komin, K., Kosack, S., Krakau, F., Krayzel, P. P., Krueger, H., Laffon, G., Lamanna, J., Lefaucheur, M., Lemoine Goumard, J. . ., P., D., Lennarz, T., Lohse, A., Lopatin, C. . ., C., V., Marandon, A., Marcowith, G., Maurin, N., Maxted, M., Mayer, T. J., L., M. C., Medina, J., Mehault, U., Menzler, M., Meyer, R., Moderski, M., Mohamed, E., Moulin, T., Murach, C. L., Naumann, M. d., Nauroi, D., Nedbal, J., Niemiec, S. J., Nolan, L., Oake, S., Ohm, E. d., Ona, B., Opitz, M., Ostrowski, I., Oya, M., Panter, R. D., Parson, M. P., Arriba, N. W., Pekeur, G., Pelletier, J., Perez, P. . ., O., B., Peyaud, S., Pita, H., Poon, G., Puehlhofer, M., Punch, A., Quirrenbach, S., Raab, M., Raue, A., Reimer, O., Reimer, M., Renaud, R. d., Lo, F., Rieger, L., Rob, S., Rosier Lee, G., Rowell, B., Rudak, C. B., Rulten, V., Sahakian, D. A., Sanchez, A., Santangelo, R., Schlickeiser, F., Schuessler, A., Schulz, U., Schwanke, S., Schwarzburg, S., Schwemmer, H., Sol, G., Spengler, F., Spie, L., Stawarz, R., Steenkamp, C., Stegmann, F., Stinzing, K., Stycz, I., Sushch, A., Szostek, R., Terrier, M., Tluczykont, C., Trichard, K., Valeriu, C. v., Eldik, G., Vasileiadi, C., Venter, A., Viana, P., Vincent, H. J., Voelk, F., Volpe, M., Vorster, S. J., Wagner, P., Wagner, M., Ward, M., Weidinger, R., White, A., Wierzcholska, P., Willmann, A., Woernlein, D., Wouter, M., Zacharia, A., Zajczyk, A. A., Zdziarski, A., Zech, H. . ., S., J. S., Perkin, R., Ojha, J., Steven, P. G., Edward, and M., Kadler

Subjects
[PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], gamma-rays: galaxies, Radio galaxy, BL Lacertae objects: individual: 1ES 1312-423, Astrophysics::High Energy Astrophysical Phenomena, Centaurus A, galaxies: active, jets [galaxies], FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 7. Clean energy, 01 natural sciences, radiation mechanisms: non-thermal, galaxies: jets, 0103 physical sciences, High Energy Stereoscopic System, Blazar, 010303 astronomy & astrophysics, individual: 1ES 1312-423 [BL Lacertae objects], Astrophysics::Galaxy Astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Spectral index, 010308 nuclear & particles physics, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Astronomy, Institut für Physik und Astronomie, Astronomy and Astrophysics, non-thermal [radiation mechanisms], Crab Nebula, galaxies [gamma-rays], jet [galaxies], 13. Climate action, Space and Planetary Science, individual: 1ES 1312–423 [BL Lacertae objects], active [galaxies], ddc:520, Spectral energy distribution, High Energy Physics::Experiment, Astrophysics - High Energy Astrophysical Phenomena, Bl Lacertae objects: individual: 1ES 1312-423, Galaxies: active, Galaxies: jets, Gamma-rays: galaxies, Radiation mechanisms: non-thermal, Fermi Gamma-ray Space Telescope
Abstract

A deep observation campaign carried out by the High Energy Stereoscopic System (H.E.S.S.) on Centaurus A enabled the discovery of gamma rays from the blazar 1ES 1312-423, two degrees away from the radio galaxy. With a differential flux at 1 TeV of (1.9 +/-0.6(stat) +/-0.4(sys)) x 10^{-13} /cm^2 /s /TeV corresponding to 0.5% of the Crab nebula differential flux and a spectral index of 2.9 +/- 0.5 (stat) +/- 0.2 (sys), 1ES 1312-423 is one of the faintest sources ever detected in the very high energy (E>100 GeV) extragalactic sky. A careful analysis using three and a half years of Fermi-LAT data allows the discovery at high energies (E>100 MeV) of a hard spectrum (index of 1.4 +/- 0.4 (stat) +/- 0.2 (sys)) source coincident with 1ES 1312-423. Radio, optical, UV and X-ray observations complete the spectral energy distribution of this blazar, now covering 16 decades in energy. The emission is successfully fitted with a synchrotron self Compton model for the non-thermal component, combined with a black-body spectrum for the optical emission from the host galaxy., 12 pages, 10 figures, accepted in MNRAS

Published
2013
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