Volume 449, Number 2, April II 2006
|Page(s)||L21 - L25|
|Published online||21 March 2006|
Letter to the Editor
INTEGRAL observations of the blazar 3C 454.3 in outburst
INAF, Osservatorio Astronomico di Trieste, via G.B. Tiepolo 11, 34131 Trieste, Italy e-mail: firstname.lastname@example.org
2 INAF, IASF-Bologna, via Gobetti 101, 40129 Bologna, Italy
3 NASA Goddard Space Flight Center, Code 661, Greenbelt, MD 20771, USA
4 Joint Center for Astrophysics, Department of Physics, University of Maryland, Baltimore County, MD 21250, USA
5 INTEGRAL Science Data Center, Chemin d'Écogia 16, 1290 Versoix, Switzerland
6 Observatoire de Genève, 51 Ch. des Maillettes, 1290 Sauverny, Switzerland
7 INAF, Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate (LC), Italy
8 ASI Science Data Center, via Galileo Galilei, 00044 Frascati, Italy
9 INAF, Osservatorio Astronomico di Brera, via Brera 28, 20121 Milano, Italy
10 Nordic Optical Telescope, Apartado 474, 38700 Santa Cruz de La Palma, Spain
11 INAF, Osservatorio Astronomico di Torino, via Osservatorio 20, 10025 Pino Torinese (TO), Italy
12 Metsähovi Radio Observatory, Metsähovintie 114, 02540 Kylmälä, Finland
13 Dipartimento di Fisica, University of Perugia, via A. Pascoli, 06123 Perugia, Italy
14 Dipartimento di Fisica e Matematica, University of Insubria, via Valleggio 11, 22100 Como, Italy
15 ESA-ESTEC, RSSD, Keplerlaan 1, Postbus 299, 2200 AG Noordwijk, The Netherlands
16 Astronomical Institute, Academy of Sciences of the Czech Republic, 251 65 Ondrejov, Czech Republic
Accepted: 12 February 2006
In Spring 2005, the blazar 3C 454.3 underwent a dramatic outburst at all wavelengths from mm to X-rays. This prompted INTEGRAL observations, accomplished in 15-18 May 2005. The source was detected by the INTEGRAL instruments from 3 to 200 keV in a bright state ( erg s-1 cm-2), at least a factor of 2-3 higher than previously observed. This is one of the brightest blazar detections achieved by INTEGRAL. During the 2.5 days of INTEGRAL monitoring, we detected a ~20% decrease in the hard X-rays (20-40 keV), indicating that we have sampled the decaying part of the flare. The decrease is less apparent in the soft X-rays (5-15 keV). The simultaneous optical variations are weakly correlated with those at soft X-rays, and not clearly correlated with those at hard X-rays. The spectral energy distribution exhibits two components, as typically seen in blazars, which can be modeled with synchrotron radiation and inverse Compton scattering occurring in a region external to the broad line region.
Key words: galaxies: active / X-rays: observations
© ESO, 2006
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