Characterizing the gamma-ray long-term variability of PKS2155 304 with HESS and Fermi-LAT

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dc.contributor.author Chen, A.
dc.contributor.author Colafrancesco, S.
dc.contributor.author Jingo, M.
dc.contributor.author Collaboration, H.E.S.S.
dc.contributor.author Abdalla, H.
dc.contributor.author Abramowski, A.
dc.contributor.author Aharonian, F.
dc.contributor.author Ait Benkhali, F.
dc.contributor.author Akhperjanian, A.G.
dc.contributor.author Andersson, T.
dc.contributor.author Angüner, E.O.
dc.contributor.author Arrieta, M.
dc.contributor.author Aubert, P.
dc.contributor.author Backes, M.
dc.contributor.author Balzer, A.
dc.contributor.author Barnard, M.
dc.contributor.author Becherini, Y.
dc.contributor.author Becker Tjus, J.
dc.contributor.author Berge, D.
dc.contributor.author Bernhard, S.
dc.contributor.author Komin, Nu.
dc.date.accessioned 2018-02-06T15:00:24Z
dc.date.available 2018-02-06T15:00:24Z
dc.date.issued 2017-02
dc.identifier.citation Abdalla, H. et al. 2017. Characterizing the gamma-ray long-term variability of PKS2155 304 with HESS and Fermi-LAT. ASTRONOMY & ASTROPHYSICS 598, Article number A39. en_ZA
dc.identifier.issn 0004-6361 (Print)
dc.identifier.issn 1432-0746 (Online)
dc.identifier.uri https://hdl.handle.net/10539/23786
dc.description.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) γ-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 βVHE = 1.10-0.13 +0.10) on timescales larger than one day. An analysis of ∼5.5 yr of HE Fermi-LAT data gives consistent results (βHE = 1.20-0.23 +0.21), on timescales 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 (β ∼ 2) seen on shorter timescales 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. en_ZA
dc.language.iso en en_ZA
dc.publisher EDP Sciences en_ZA
dc.rights © ESO, 2017 en_ZA
dc.subject Galaxies: active en_ZA
dc.subject BL Lacertae objects: individual: PKS 2155-304 en_ZA
dc.subject Galaxies: jets en_ZA
dc.subject Galaxies: nuclei en_ZA
dc.subject Gamma rays: galaxies en_ZA
dc.subject Radiation mechanisms: non-thermal en_ZA
dc.subject Fighter aircraft en_ZA
dc.subject Galaxies en_ZA
dc.subject Power spectral density en_ZA
dc.subject Relativity en_ZA
dc.subject Spectral density en_ZA
dc.subject Bl lacertae objects: individual: pks 2155-304 en_ZA
dc.title Characterizing the gamma-ray long-term variability of PKS2155 304 with HESS and Fermi-LAT en_ZA
dc.type Article en_ZA
dc.journal.volume 598 en_ZA
dc.journal.title ASTRONOMY & ASTROPHYSICS en_ZA
dc.description.librarian EM2018 en_ZA
dc.citation.doi 10.1051/0004-6361/201629419 en_ZA


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