2006/04/30 by L. Foschini, G. Tagliaferri, E. Pian +6 · 1 citation
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Radio Astronomy Observations and Technology #astro-ph
paper · pdf · doi:10.1051/0004-6361:20064959
8 pages, 6 figures. Accepted for publication on A&A Main Journal. Revision of the English grammar
arxiv created 2006/06/21 · openalex publication_date 2006/08/04 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/04
At the end of March 2004, the blazar S5 0716+714 underwent an optical outburst that prompted for quasi-simultaneous target-of-opportunity observations with the INTEGRAL and XMM-Newton satellites. In this paper, we report the results of the XMM-Newton and INTEGRAL OMC data analysis. The X-ray spectrum is well-represented by a concave broken power-law model, with the break at about 2 keV. In the framework of the synchrotron self-Compton model, the softer part of the spectrum, which is described by a power law of index (), is probably due to synchrotron emission, while the harder part of the spectrum, which has , is due to inverse Compton emission. The blazar shows the long and short-term variability typical of low-frequency peaked BL Lac (LBL): the former is manifested by a gradual decrease in the optical flux from the peak as observed by ground telescopes at the end of March 2004, while the latter is characterized by soft X-ray and optical flares on time scales from a few thousand seconds to few hours. We can follow spectral variations on sub-hour time scales and study their correlation with the flux variability. We find evidence that the peak energy of the time-resolved spectra is increasing with flux. The modeling of the spectral energy distribution compared with archival observations suggests that the long-term variability (from outburst to quiescence or viceversa) could be due to a change in the injected power, while the short-term variability (flares) could be explained with changes in the slope of the distribution of the electrons.