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Simultaneous Observations of PKS 2155--304 with H.E.S.S., Fermi, RXTE and ATOM [electronic resource] : Spectral Energy Distributions and Variability in a Low State

Published
Washington, D.C. : United States. Dept. of Energy. Office of Science, 2009.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Physical Description
L150 : digital, PDF file
Additional Creators
SLAC National Accelerator Laboratory, United States. Department of Energy. Office of Science, and United States. Department of Energy. Office of Scientific and Technical Information
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Summary
We report on the first simultaneous observations that cover the optical, X-ray, and high-energy gamma-ray bands of the BL Lac object PKS 2155-304. The gamma-ray bands were observed for 11 days, between 2008 August 25 and 2008 September 6 (MJD 54704-54715), jointly with the Fermi Gamma-ray Space Telescope and the HESS atmospheric Cherenkov array, providing the first simultaneous MeV-TeV spectral energy distribution (SED) with the new generation of γ-ray telescopes. The ATOM telescope and the RXTE and Swift observatories provided optical and X-ray coverage of the low-energy component over the same time period. The object was close to the lowest archival X-ray and very high energy (VHE; >100 GeV) state, whereas the optical flux was much higher. The light curves show relatively little (≈30%) variability overall when compared to past flaring episodes, but we find a clear optical/VHE correlation and evidence for a correlation of the X-rays with the high-energy spectral index. Contrary to previous observations in the flaring state, we do not find any correlation between the X-ray and VHE components. Although synchrotron self-Compton models are often invoked to explain the SEDs of BL Lac objects, the most common versions of these models are at odds with the correlated variability we find in the various bands for PKS 2155-304.
Report Numbers
E 1.99:slac-pub-13591
slac-pub-13591
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Other Subject(s)
Note
Published through SciTech Connect.
05/07/2009.
"slac-pub-13591"
"arXiv:0903.2924"
Astrophysical Journal 696 2 ISSN 0004-637X; ASJOAB FT
Borrel, V.; Aharonian, F.; Behera, B.; Anton, G.; Akhperjanian, A.G.; Barres de Almeida, U.; Bazer-Bachi, A.R.; Becherini, Y.; Bernlohr, K.; Boisson, C.; Bochow, A.; Brion, E.; Brucker, J.; Brun, P.; Buhler, R.; Bulik, T.; Busching, I.; Boutelier, T.; Chadwick, P.M.; Charbonnier, A.; Chaves, R.C.G.
Funding Information
AC02-76SF00515
View MARC record | catkey: 13804424