Characterizing the gamma-ray long-term variability of PKS 2155-304 with H.E.S.S. and Fermi-LAT
Abstract
Studying the temporal variability of BL Lac objects at the highest energies provides unique insights into the extreme physical processes occurring in relativistic jets and in the vicinity of super-massive black holes. To this end, the long-term variability of the BL Lac object PKS 2155-304 is analyzed in the high (HE, 100 MeV < E < 300 GeV) and very high energy (VHE, E > 200 GeV) gamma-ray domain. Over the course of ~9 yr of H.E.S.S observations the VHE light curve in the quiescent state is consistent with a log-normal behavior. The VHE variability in this state is well described by flicker noise (power-spectral-density index {\ss}_VHE = 1.10 +0.10 -0.13) on time scales larger than one day. An analysis of 5.5 yr of HE Fermi LAT data gives consistent results ({\ss}_HE = 1.20 +0.21 -0.23, on time scales larger than 10 days) compatible with the VHE findings. The HE and VHE power spectral densities show a scale invariance across the probed time ranges. A direct linear correlation between the VHE and HE fluxes could neither be excluded nor firmly established. These long-term-variability properties are discussed and compared to the red noise behavior ({\ss} ~ 2) seen on shorter time scales during VHE-flaring states. The difference in power spectral noise behavior at VHE energies during quiescent and flaring states provides evidence that these states are influenced by different physical processes, while the compatibility of the HE and VHE long-term results is suggestive of a common physical link as it might be introduced by an underlying jet-disk connection.
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@article{arxiv.1610.03311,
title = {Characterizing the gamma-ray long-term variability of PKS 2155-304 with H.E.S.S. and Fermi-LAT},
author = {H. E. S. S. Collaboration and H. Abdalla and A. Abramowski and F. Aharonian and F. Ait Benkhali and A. G. Akhperjanian T. Andersson and M. Arrieta and P. Aubert and M. Backes and A. Balzer and M. Barnard and Y. Becherini and J. Becker Tjus and D. Berge S. Bernhard and K. Bernlöhr and R. Blackwell and M. Böttcher and C. Boisson and J. Bolmont and P. Bordas and J. Bregeon and F. Brun and P. Brun and M. Bryan and T. Bulik and M. Capasso and J. Carr S. Casanova and M. Cerruti and N. Chakraborty and R. Chalme-Calvet and R. C. G. Chaves and A. Chen and J. Chevalier and M. Chrétien and S. Colafrancesco and G. Cologna and B. Condon and J. Conrad and Y. Cui and I. D. Davids and J. Decock and B. Degrange and C. Deil and J. Devin and P. deWilt and L. Dirson and A. Djannati-Ataï and W. Domainko and A. Donath and L. O'C. Drury and G. Dubus and K. Dutson and J. Dyks and T. Edwards and K. Egberts and P. Eger and J. -P. Ernenwein and S. Eschbach and C. Farnier and S. Fegan and M. V. Fernandes and A. Fiasson and G. Fontaine and A. Förster and S. Funk and M. Füßling and S. Gabici M. Gajdus and Y. A. Gallant and T. Garrigoux and G. Giavitto and B. Giebels and J. F. Glicenstein and D. Gottschall and A. Goyal and M. -H. Grondin and D. Hadasch and J. Hahn and M. Haupt and J. Hawkes and G. Heinzelmann and G. Henri and G. Hermann and O. Hervet and J. A. Hinton and W. Hofmann and C. Hoischen and M. Holler and D. Horns and A. Ivascenko and A. Jacholkowska and M. Jamrozy and M. Janiak and D. Jankowsky and F. Jankowsky and M. Jingo and T. Jogler and L. Jouvin and I. Jung-Richardt and M. A. Kastendieck and K. Katarzyński and U. Katz and D. Kerszberg and B. Khélifi and M. Kieffer and J. King and S. Klepser and D. Klochkov and W. Kluźniak and D. Kolitzus and Nu. Komin and K. Kosack and S. Krakau and M. Kraus and F. Krayzel and P. P. Krüger and H. Laffon and G. Lamanna and J. Lau and J. -P. Lees and J. Lefaucheur and V. Lefranc and A. Lemière and M. Lemoine-Goumard and J. -P. Lenain and E. Leser and T. Lohse and M. Lorentz and R. Liu and R. López-Coto and I. Lypova and V. Marandon and A. Marcowith and C. Mariaud and R. Marx and G. Maurin and N. Maxted and M. Mayer and P. J. Meintjes and M. Meyer and A. M. W. Mitchell and R. Moderski and M. Mohamed and L. Mohrmann and K. Morå and E. Moulin and T. Murach and M. deNaurois and F. Niederwanger and J. Niemiec and L. Oakes and P. O'Brien and H. Odaka and S. Öttl and S. Ohm and M. Ostrowski and I. Oya and M. Padovani and M. Panter and R. D. Parsons and N. W. Pekeur and G. Pelletier and C. Perennes and P. -O. Petrucci and B. Peyaud and Q. Piel S. Pita and H. Poon and D. Prokhorov and H. Prokoph and G. Pühlhofer and M. Punch and A. Quirrenbach and S. Raab and A. Reimer and O. Reimer and M. Renaud and R. delosReyes and F. Rieger and C. Romoli and S. Rosier-Lees and G. Rowell and B. Rudak and C. B. Rulten and V. Sahakian and D. Salek and D. A. Sanchez and A. Santangelo and M. Sasaki and R. Schlickeiser and F. Schüssler and A. Schulz and U. Schwanke and S. Schwemmer and M. Settimo and A. S. Seyffert and N. Shafi and I. Shilon and R. Simoni and H. Sol and F. Spanier and G. Spengler and F. Spies and Ł. Stawarz and R. Steenkamp and C. Stegmann and F. Stinzing and K. Stycz and I. Sushch and J. -P. Tavernet and T. Tavernier and A. M. Taylor and R. Terrier and L. Tibaldo and D. Tiziani and M. Tluczykont and C. Trichard and R. Tuffs and Y. Uchiyama and D. J. van der Walt and C. vanEldik and C. vanRensburg and B. vanSoelen and G. Vasileiadis and J. Veh and C. Venter and A. Viana and P. Vincent and J. Vink and F. Voisin and H. J. Völk and T. Vuillaume and Z. Wadiasingh and S. J. Wagner and P. Wagner and R. M. Wagner R. White and A. Wierzcholska and P. Willmann and A. Wörnlein and D. Wouters and R. Yang and V. Zabalza and D. Zaborov and M. Zacharias and A. A. Zdziarski and A. Zech and F. Zefi and A. Ziegler and N. Żywucka},
journal= {arXiv preprint arXiv:1610.03311},
year = {2017}
}
Comments
11 pages, 16 figures