arXiv · 1802.07611
H.E.S.S. discovery of very high energy gamma-ray emission from PKS 0625-354
Abstract
PKS 0625-354 (z=0.055) was observed with the four H.E.S.S. telescopes in 2012 during 5.5 hours. The source was detected above an energy threshold of 200 GeV at a significance level of 6.1$\sigma$. No significant variability is found in these observations. The source is well described with a power-law spectrum with photon index $\Gamma =2.84 \pm 0.50_{stat} \pm 0.10_{syst}$ and normalization (at $E_0$=1.0 TeV) $N_0(E_0)=(0.58 \pm 0.22_{stat} \pm 0.12_{syst})\times10^{-12}$ TeV$^{-1}$cm$^{-2}$s$^{-1}$. Multi-wavelength data collected with Fermi-LAT, Swift-XRT, Swift-UVOT, ATOM and WISE are also analysed. Significant variability is observed only in the Fermi-LAT $\gamma$-ray and Swift-XRT X-ray energy bands. Having a good multi-wavelength coverage from radio to very high energy, we performed a broadband modelling from two types of emission scenarios. The results from a one zone lepto-hadronic, and a multi-zone leptonic models are compared and discussed. On the grounds of energetics, our analysis favours a leptonic multi-zone model. Models associated to the X-ray variability constraint supports previous results suggesting a BL Lac nature of PKS 0625-354, with, however, a large-scale jet structure typical of a radio galaxy.
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H. E. S. S. Collaboration, H. Abdalla, A. Abramowski, F. Aharonian, F. Ait Benkhali, A. G. Akhperjanian, T. Andersson, E. O. Angüner, M. Arrieta, P. Aubert, M. Backes, A. Balzer, M. Barnard, Y. Becherini, J. Becker Tjus, D. Berge, S. Bernhard, K. Bernlöhr, R. Blackwell, M. Böttcher, 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, R. C. G. Chaves, A. Chen, J. Chevalier, M. Chrétien, S. Colafrancesco, G. Cologna, B. Condon, J. Conrad, Y. Cui, I. D. Davids, J. Decock, B. Degrange, C. Deil, J. Devin, P. deWilt, L. Dirson, A. Djannati-Ataï, W. Domainko, A. Donath, L. O'C. Drury, G. Dubus, K. Dutson, J. Dyks, M. Dyrda, T. Edwards, K. Egberts, P. Eger, J. -P. Ernenwein, S. Eschbach, C. Farnier, S. Fegan, M. V. Fernandes, A. Fiasson, G. Fontaine, A. Förster, S. Funk, M. Füßling, S. Gabici, M. Gajdus, Y. A. Gallant, T. Garrigoux, G. Giavitto, B. Giebels, J. F. Glicenstein, D. Gottschall, A. Goyal, M. -H. Grondin, D. Hadasch, J. Hahn, M. Haupt, J. Hawkes, G. Heinzelmann, G. Henri, G. Hermann, O. Hervet, J. A. Hinton, W. Hofmann, C. Hoischen, M. Holler, D. Horns, A. Ivascenko, A. Jacholkowska, M. Jamrozy, M. Janiak, D. Jankowsky, F. Jankowsky. 2018-02-21. H.E.S.S. discovery of very high energy gamma-ray emission from PKS 0625-354. https://doi.org/10.1093/mnras%2Fsty439
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