Simultaneous X-ray and optical observations of S5 0716+714 after the outburst of March 2004
Simultaneous X-ray and optical observations of S5 0716+714 after the outburst of March 2004
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DOI：
10.1051/0004-6361:20064959
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发表时间：
2006-04
影响因子：
6.5
通讯作者：
L. Foschini;G. Tagliaferri;E. Pian;G. Ghisellini;A. Treves;L. Maraschi;F. Tavecchio;G. Cocco;Simon Rosen
中科院分区：
文献类型：
--
作者：
L. Foschini;G. Tagliaferri;E. Pian;G. Ghisellini;A. Treves;L. Maraschi;F. Tavecchio;G. Cocco;Simon Rosen
2004年3月底，耀变体S5 0716+714经历了一次光学爆发，促使INTEGRAL和XMM-牛顿卫星进行了准同时的机会目标观测。在本文中，我们报告的XMM-牛顿和积分OMC数据分析的结果。X射线光谱是很好地代表了一个凹破幂律模型，在约2千电子伏的突破。在同步辐射自康普顿模型的框架下，光谱中较软的部分，由指数为$\alpha \simeq 1.8$（$f_\nu \propto \nu^{-\alpha}$）的幂律描述，可能是由于同步辐射，而光谱中较硬的部分，具有$\alpha \simeq 1$，是由于逆康普顿辐射。耀变体显示了低频峰值BL Lac（LBL）的典型长期和短期变化：前者表现为2004年3月底地面望远镜观察到的峰值光通量逐渐减少，而后者的特征是软X射线和光学耀斑，时间尺度从几千秒到几小时。我们可以在小时以下的时间尺度上跟踪光谱变化，并研究它们与通量变化的相关性。我们发现的证据表明，峰值能量的时间分辨光谱增加通量。与档案观测相比，光谱能量分布的建模表明，长期的变化（从爆发到静止或反之亦然）可能是由于注入功率的变化，而短期的变化（耀斑）可以解释与电子分布的斜率变化。
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.