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HESS discovery of very high energy gamma-ray emission from PKS 0625-354

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posted on 2018-05-17, 15:04 authored by H Abdalla, A Abramowski, F Aharonian, FA Benkhali, AG Akhperjanian, T Andersson, EO Anguner, M Arrieta, P Aubert, M Backes, A Balzer, M Barnard, Y Becherini, JB Tjus, D Berge, S Bernhard, K Bernlohr, R Blackwell, M Bottcher, C Boisson, J Bolmont, P Bordas, J Bregeon, F Brun, P Brun, M Bryan, T Bulik, M Capasso, J Carr, S Casanova, M Cerruti, N Chakraborty, R Chalme-Calvet, RCG Chaves, A Chen, J Chevalier, M Chretien, S Colafrancesco, G Cologna, B Condon, J Conrad, Y Cui, ID Davids, J Decock, B Degrange, C Deil, J Devin, P deWilt, L Dirson, A Djannati-Atai, W Domainko, A Donath, LO Drury, G Dubus, K Dutson, J Dyks, M Dyrda, T Edwards, K Egberts, P Eger, J-P Ernenwein, S Eschbach, C Farnier, S Fegan, MV Fernandes, A Fiasson, G Fontaine, A Forster, S Funk, M Fussling, S Gabici, M Gajdus, YA Gallant, T Garrigoux, G Giavitto, B Giebels, JF Glicenstein, D Gottschal, A Goya, M-H Grondin, D Hadasch, J Hahn, M Haupt, J Hawkes, G Heinzelmann, G Henri, G Hermann, O Hervet, JA Hinton, W Hofmann, C Hoischen, M Holler, D Horns, A Ivascenko, A Jacholkowska, M Jamrozy, M Janiak, D Jankowsky, F Jankowsky, M Jingo, T Jogler, L Jouvin, I Jung-Richardt, MA Kastendieck, K Katarzynski, U Katz, D Kerszberg, B Khelifi, M Kieffer, J King, S Klepser, D Klochkov, W Kluzniak, D Kolitzus, N Komin, K Kosack, S Krakau, M Kraus, F Krayzel, PP Kruger, H Laffon, G Lamanna, J Lau, J-P Lees, J Lefaucheur, V Lefranc, A Lemiere, M Lemoine-Goumard, J-P Lenain, E Leser, T Lohse, M Lorentz, R Liu, R Lopez-Coto, I Lypova, V Marandon, A Marcowith, C Mariaud, R Marx, G Maurin, N Maxted, M Mayer, PJ Meintjes, M Meyer, AMW Mitchell, R Moderski, M Mohamed, L Mohrmann, K Mora, E Moulin, T Murach, M de Naurois, F Niederwanger, J Niemiec, L Oakes, P O'Brien, H Odaka, S Ottl, S Ohm, M Ostrowski, I Oya, M Padovani, M Panter, RD Parsons, NW Pekeur, G Pelletier, C Perennes, P-O Petrucci, B Peyaud, Q Piel, S Pita, H Poon, D Prokhorov, H Prokoph, G Puhlhofer, M Punch, A Quirrenbach, S Raab, A Reimer, O Reimer, M Renaud, R de los Reyes, F Rieger, C Romoli, S Rosier-Lees, G Rowel, B Rudak, CB Rulten, V Sahakian, D Salek, DA Sanchez, A Santangelo, M Sasaki, R Schlickeiser, F Schussler, A Schulz, U Schwanke, S Schwemmer, M Settimo, AS Seyffert, N Shafi, I Shilon, R Simoni, H Sol, F Spanier, G Spengler, F Spies, L Stawarz, R Steenkamp, C Stegmann, F Stinzing, K Stycz, I Sushch, J-P Tavernet, T Tavernier, AM Taylor, R Terrier, L Tibaldo, D Tiziani, M Tluczykont, C Trichard, R Tuffs, Y Uchiyama, DJ van der Walt, C van Eldik, C van Rensburg, B van Soelen, G Vasileiadis, J Veh, C Venter, A Viana, P Vincent, J Vink, F Voisin, HJ Volk, T Vuillaume, Z Wadiasingh, SJ Wagner, P Wagner, RM Wagner, R White, A Wierzcholska, P Willmann, A Wornlein, D Wouters, R Yang, V Zabalza, D Zaborov, M Zacharias, R Zanin, AA Zdziarski, A Zech, F Zefi, A Ziegler, N Zywucka
PKS 0625−354 (z = 0.055) was observed with the four High Energy Stereoscopic System (H.E.S.S.) telescopes in 2012 during 5.5 h. The source was detected above an energy threshold of 200 GeV at a significance level of 6.1σ. No significant variability is found in these observations. The source is well described with a power-law spectrum with photon index = 2.84 ± 0.50stat ± 0.10syst and normalization (at E0 = 1.0 TeV) N0(E0) = (0.58 ± 0.22stat ± 0.12syst) × 10−12 TeV−1 cm−2 s−1. Multiwavelength data collected with Fermi-LAT, Swift-XRT, Swift-UVOT, ATOM and WISE are also analysed. Significant variability is observed only in the Fermi-LAT γ -ray and Swift-XRT X-ray energy bands. Having a good multiwavelength coverage from radio to very high energy, we performed a broad-band modelling from two types of emission scenarios. The results from a one zone lepto-hadronic and a multizone leptonic models are compared and discussed. On the grounds of energetics, our analysis favours a leptonic multizone model. Models associated to the X-ray variability constraint support previous results, suggesting a BL Lac nature of PKS 0625−354 with, however, a large-scale jet structure typical of a radio galaxy.


The support of the Namibian authorities and of the University of Namibia in facilitating the construction and operation of H.E.S.S. is gratefully acknowledged, as is the support by the German Ministry for Education and Research (BMBF), the Max Planck Society, the German Research Foundation (DFG), the Alexander von Humboldt Foundation, the Deutsche Forschungsgemeinschaft, the French Ministry for Research, the CNRS-IN2P3 and the Astroparticle Interdisciplinary Programme of the CNRS, the U.K. Science and Technology Facilities Council (STFC), the IPNP of the Charles University, the Czech Science Foundation, the Polish National Science Centre, the South African Department of Science and Technology and National Research Foundation, the University of Namibia, the National Commission on Research, Science and Technology of Namibia (NCRST), the Innsbruck University, the Austrian Science Fund (FWF), and the Austrian Federal Ministry for Science, Research and Economy, the University of Adelaide and the Australian Research Council, the Japan Society for the Promotion of Science, and the University of Amsterdam. We appreciate the excellent work of the technical support staff in Berlin, Durham, Hamburg, Heidelberg, Palaiseau, Paris, Saclay, and in Namibia in the construction and operation of the equipment. This work was benefitted from services provided by the H.E.S.S. Virtual Organization, supported by the national resource providers of the EGI Federation. AW is supported by the Foundation for Polish Science (FNP). OH thanks the U.S. National Science Foundation for support under grant PHY-1307311 and the Observatoire de Paris for financial support with ATER position. RCGC is funded by EU FP7 Marie Curie under grant agreement No. PIEF-GA-2012-332350.



Monthly Notices of the Royal Astronomical Society, 2018, 476 (3), pp. 4187-4198 (12)

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/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy


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