X-ray spectral evolution of TeV BL Lacertae objects : eleven years of observations with BeppoSAX, XMM-Newton and Swift satellites
In: Astronomy and astrophysics (Berlin. Print), Jg. 478 (2008), Heft 2, S. 395-401
Online
academicJournal
- print, 1/2 p
Zugriff:
Context. Many of the extragalactic sources detected in γ rays at TeV energies are BL Lac objects. In particular, they belong to the subclass of high frequency peaked BL Lacs (HBLs), as their spectral energy distributions exhibit a first peak in the X-ray band. At a closer look, their X-ray spectra appear to be generally curved into a log-parabolic shape. In a previous investigation of Mrk 421, two correlations were found between the spectral parameters. One involves the height Sp increasing with the position Ep of the first peak; this was interpreted as a signature of synchrotron emission from relativistic electrons. The other involves the curvature parameter b decreasing as Ep increases; this points toward statistical/stochastic acceleration processes for the emitting electrons. Aims. We analyse X-ray spectra of several TeV HBLs to pinpoint their behaviours in the Ep - Sp and Ep - b planes and to compare them with Mrk 421. Methods. We perfom X-ray spectral analyses of a sample of 15 BL Lacs. We report the whole set of observations obtained with the BeppoSAX, XMM-Newton and Swift satellites between 29/06/96 and 07/04/07. We focus on five sources (PKS 0548-322, 1H 1426+418, Mrk 501, 1ES 1959+650, PKS 2155-304) whose X-ray observations warrant detailed searching of correlations or trends. Results. Within our database, we find that four out of five sources, namely PKS 0548-322, 1H 1426+418, Mrk 501 and 1ES 1959+650, follow similar trends as Mrk 421 in the Ep - Sp plane, while PKS 2155-304 differs. As for the Ep - b plane, all TeV HBLs follow a similar behaviour. Conclusions. The trends exhibited by Mrk 421 appear to be shared by several TeV HBLs, such as to warrant discussing predictions from the X-ray spectral evolution to that of TeV emissions.
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X-ray spectral evolution of TeV BL Lacertae objects : eleven years of observations with BeppoSAX, XMM-Newton and Swift satellites
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Autor/in / Beteiligte Person: | MASSARO, F ; TRAMACERE, A ; CAVALIERE, A ; PERRI, M ; GIOMMI, P |
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Zeitschrift: | Astronomy and astrophysics (Berlin. Print), Jg. 478 (2008), Heft 2, S. 395-401 |
Veröffentlichung: | Les Ulis: EDP Sciences, 2008 |
Medientyp: | academicJournal |
Umfang: | print, 1/2 p |
ISSN: | 0004-6361 (print) |
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