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Search for extended γ-ray emission around AGN with H.E.S.S. and Fermi-LAT.

Abramowski, A. and Aharonian, F. and Ait Benkhali, F. and Akhperjanian, A.G. and Angüner, E. and Anton, G. and Backes, M. and Balenderan, S. and Balzer, A. and Barnacka, A. and Becherini, Y. and Becker Tjus, J. and Bernlöhr, K. and Birsin, E. and Bissaldi, E. and Biteau, J. and Böttcher, M. and Boisson, C. and Bolmont, J. and Bordas, P. and Brucker, J. and Brun, F. and Brun, P. and Bulik, T. and Carrigan, S. and Casanova, S. and Chadwick, P.M. and Chalme-Calvet, R. and Chaves, R.C.G. and Cheesebrough, A. and Chrétien, M. and Colafrancesco, S. and Cologna, G. and Conrad, J. and Couturier, C. and Cui, Y. and Dalton, M. and Daniel, M.K. and Davids, I.D. and Degrange, B. and Deil, C. and deWilt, P. and Dickinson, H.J. and Djannati-Atäı, A. and Domainko, W. and Drury, L.O'C. and Dubus, G. and Dutson, K. and Dyks, J. and Dyrda, M. and Edwards, T. and Egberts, K. and Eger, P. and Espigat, P. and Farnier, C. and Fegan, S. and Feinstein, F. and Fernandes, M.V. and Fernandez, D. and Fiasson, A. and Fontaine, G. and Förster, A. and Füßling, M. and Gajdus, M. and Gallant, Y.A. and Garrigoux, T. and Giavitto, G. and Giebels, B. and Glicenstein, J.F. and Grondin, M.-H. and Grudzińska, M. and Häffner, S. and Hahn, J. and Harris, J. and Heinzelmann, G. and Henri, G. and Hermann, G. and Hervet, O. and Hillert, A. and Hinton, J.A. and Hofmann, W. and Hofverberg, P. and Holler, M. and Horns, D. and Jacholkowska, A. and Jahn, C. and Jamrozy, M. and Janiak, M. and Jankowsky, F. and Jung, I. and Kastendieck, M.A. and Katarzyński, K. and Katz, U. and Kaufmann, S. and Khélifi, B. and Kieffer, M. and Klepser, S. and Klochkov, D. and Kluźniak, W. and Kneiske, T. and Kolitzus, D. and Komin, Nu. and Kosack, K. and Krakau, S. and Krayzel, F. and Krüger, P.P. and Laffon, H. and Lamanna, G. and Lefaucheur, J. and Lemière, A. and Lemoine-Goumard, M. and Lenain, J.-P. and Lohse, T. and Lopatin, A. and Lu, C.-C. and Marandon, V. and Marcowith, A. and Marx, R. and Maurin, G. and Maxted, N. and Mayer, M. and McComb, T.J.L. and Méhault, J. and Meintjes, P.J. and Menzler, U. and Meyer, M. and Moderski, R. and Mohamed, M. and Moulin, E. and Murach, T. and Naumann, C.L. and de Naurois, M. and Niemiec, J. and Nolan, S.J. and Oakes, L. and Odaka, H. and Ohm, S. and de Oña Wilhelmi, E. and Opitz, B. and Ostrowski, M. and Oya, I. and Panter, M. and Parsons, R.D. and Paz Arribas, M. and Pekeur, N.W. and Pelletier, G. and Perez, J. and Petrucci, P.-O. and Peyaud, B. and Pita, S. and Poon, H. and Pühlhofer, G. and Punch, M. and Quirrenbach, A. and Raab, S. and Raue, M. and Reichardt, I. and Reimer, A. and Reimer, O. and Renaud, M. and de los Reyes, R. and Rieger, F. and Rob, L. and Romoli, C. and Rosier-Lees, S. and Rowell, G. and Rudak, B. and Rulten, C.B. and Sahakian, V. and Sanchez, D.A. and Santangelo, A. and Schlickeiser, R. and Schüssler, F. and Schulz, A. and Schwanke, U. and Schwarzburg, S. and Schwemmer, S. and Sol, H. and Spengler, G. and Spies, F. and Stawarz, Ł. and Steenkamp, R. and Stegmann, C. and Stinzing, F. and Stycz, K. and Sushch, I. and Tavernet, J.-P. and Tavernier, T. and Taylor, A.M. and Terrier, R. and Tluczykont, M. and Trichard, C. and Valerius, K. and van Eldik, C. and van Soelen, B. and Vasileiadis, G. and Venter, C. and Viana, A. and Vincent, P. and Völk, H.J. and Volpe, F. and Vorster, M. and Vuillaume, T. and Wagner, S.J. and Wagner, P. and Wagner, R.M. and Ward, M. and Weidinger, M. and Weitzel, Q. and White, R. and Wierzcholska, A. and Willmann, P. and Wörnlein, A. and Wouters, D. and Yang, R. and Zabalza, V. and Zacharias, M. and Zdziarski, A.A. and Zech, A. and Zechlin, H.-S. and Malyshev, D. (2014) 'Search for extended γ-ray emission around AGN with H.E.S.S. and Fermi-LAT.', Astronomy and astrophysics., 562 . A145.

Abstract

Context. Very-high-energy (VHE; E > 100 GeV) γ-ray emission from blazars inevitably gives rise to electron-positron pair production through the interaction of these γ-rays with the extragalactic background light (EBL). Depending on the magnetic fields in the proximity of the source, the cascade initiated from pair production can result in either an isotropic halo around an initially beamed source or a magnetically broadened cascade flux. Aims. Both extended pair-halo (PH) and magnetically broadened cascade (MBC) emission from regions surrounding the blazars 1ES 1101-232, 1ES 0229+200, and PKS 2155-304 were searched for using VHE γ-ray data taken with the High Energy Stereoscopic System (H.E.S.S.) and high-energy (HE; 100 MeV < E < 100 GeV) γ-ray data with the Fermi Large Area Telescope (LAT). Methods. By comparing the angular distributions of the reconstructed γ-ray events to the angular profiles calculated from detailed theoretical models, the presence of PH and MBC was investigated. Results. Upper limits on the extended emission around 1ES 1101-232, 1ES 0229+200, and PKS 2155-304 are found to be at a level of a few per cent of the Crab nebula flux above 1 TeV, depending on the assumed photon index of the cascade emission. Assuming strong extra-Galactic magnetic field (EGMF) values, >10-12   G, this limits the production of pair haloes developing from electromagnetic cascades. For weaker magnetic fields, in which electromagnetic cascades would result in MBCs, EGMF strengths in the range (0.3−3)× 10-15 G were excluded for PKS 2155-304 at the 99% confidence level, under the assumption of a 1 Mpc coherence length.

Item Type:Article
Keywords:Gamma rays: galaxies, Galaxies: magnetic fields, Intergalactic medium, BL Lacertae objects: individual: PKS 2155-304, BL Lacertae objects: individual: 1ES 1101-232, BL Lacertae objects: individual: 1ES 0229+200.
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Status:Peer-reviewed
Publisher Web site:http://dx.doi.org/10.1051/0004-6361/201322510
Publisher statement:Reproduced with permission from Astronomy & Astrophysics, © ESO, 2014.
Date accepted:12 January 2014
Date deposited:15 July 2014
Date of first online publication:February 2014
Date first made open access:No date available

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