Open AccessX-Ray/UV/Optical Follow-up of the Blazar PKS 2155-304 after the Giant TeV Flares of 2006 July
Author(s) -
L. Foschini,
G. Ghisellini,
F. Tavecchio,
A. Treves,
L. Maraschi,
M. Gliozzi,
C. M. Raiteri,
M. Villata,
E. Pian,
G. Tagliaferri,
G. Tosti,
R. M. Sambruna,
G. Malaguti,
G. Di Cocco,
P. Giommi
Publication year - 2007
Publication title -
the astrophysical journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.376
H-Index - 489
eISSN - 1538-4357
pISSN - 0004-637X
DOI - 10.1086/513271
Subject(s) - blazar , physics , astrophysics , flare , spectral energy distribution , flux (metallurgy) , wavelength , synchrotron , normalization (sociology) , gamma ray , nuclear physics , galaxy , optics , materials science , metallurgy , sociology , anthropology
We present all the publicly available data, from optical/UV wavelengths(UVOT) to X-rays (XRT, BAT), obtained from Swift observations of the blazar PKS2155-304, performed in response to the rapid alert sent out after the strongTeV activity (up to 17 Crab flux level at E > 200 GeV) at the end of July 2006.The X-ray flux increased by a factor of 5 in the 0.3-10 keV energy band and bya factor of 1.5 at optical/UV wavelengths, with roughly one day of delay. Thecomparison of the spectral energy distribution built with dataquasi-simultaneous to the TeV detections shows an increase of the overallnormalization with respect to archival data, but only a small shift of thefrequency of the synchrotron peak that remains consistent with the valuesreported in past observations when the TeV activity was much weaker.Comment: 13 pages, 3 figures. ApJ Letters, accepted for publicatio
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