Simultaneous X-ray and optical observations of S5 0716+714 after the outburst of March 2004

Abstract

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 $\alpha \simeq 1.8$ ($f_{\nu }\propto {\nu }^{-\alpha }$), is probably due to synchrotron emission, while the harder part of the spectrum, which has $\alpha \simeq 1$, 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.

8 pages, 6 figures. Accepted for publication on A&A Main Journal. Revision of the English grammar

References in corpus (1)

• Testing the inverse-Compton catastrophe scenario in the intra-day variable blazar S5 0716+71. I. Simultaneous broadband observations during November 2003

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• Multi-color Near Infra-red Intra-day and Short Term Variability of the Blazar S5 0716+714
• Blazar nuclei in radio-loud narrow-line Seyfert 1?
• Disentangling the synchrotron and Inverse Compton variability in the X-ray emission of the intermediate BL Lac object S5 0716+71
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• XMM-Newton observations of the TeV BL Lac object PKS 2155--304 in 2006: signature of inverse Compton X-ray emission?
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• AGILE and Swift simultaneous observations of the blazar S50716+714 during the bright flare of October 2007
• Infrared to X-ray observations of PKS 2155-304 in a low state
• Redshift Limits of BL Lacertae Objects from Optical Spectroscopy
• Multi-color optical monitoring of the BL Lacertae object S5 0716+714 during the 2012 outburst
• The polyhedral nature of LINERs: An XMM-Newton view of LINERs in radio galaxies
• X-ray timing and spectral variability properties of blazars S5 0716+714, OJ 287, Mrk 501, and RBS 2070
• Optical Quasi-periodic Oscillations in the TESS light curves of three blazars
• Probing the Transition Between the Synchrotron and Inverse-compton Spectral Components of 1ES 1959+650
• A synchrotron self-Compton model with low energy electron cut-off for the blazar S5 0716+714
• Using the Markov Chain Monte Carlo method to study the physical properties GeV-TeV BL Lac objects
• Patterns of variability in gamma-ray blazars
• Variability Study and Searching for QPOs with day-like periods in the blazar S5 0716+714 with TESS
• Optical Monitoring and Long-term Optical Spectral Variability of BL Lacertae Object S5 0716+714