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arXiv 1102.4959astro-ph.HEastro-ph.CO
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康普顿过程在明亮的AGN MCG +8-11-11

Compton processes in the bright AGN MCG+8-11-11

S. Soldi, V. Beckmann, N. Gehrels, P. Lubinski, C. Ricci, R. Walter

摘要:

本文介绍了用INTEGRAL和SWIFT观测到的塞弗特1.5星系MCG+8-11-11的硬X射线辐射特性的初步结果。我们分析了2009年10月之前的所有INTEGRAL IBIS/ISGRI数据,以及2009年8月和10月进行的两次SWIFT/XRT快照观测,这两次观测与MCG+8-11-11的INTEGRAL定点观测准同时进行。硬X射线通量和光谱斜率之间没有相关性,而高能截止点的位置被发现在INTEGRAL观测过程中发生了变化。这表明康普顿化介质的温度从kT = 30-50 keV的最小值变化到大于100-150 keV的值。没有发现明显的康普顿反射,3 sigma的上限R < 0.2,在112 keV没有发现任何谱线,正如之前HEAT观测所声称的(112 keV通量F < 2.4e-4 ph/cm^2/s)。MCG+8-11-11的变化行为与IC 4329 A相似,在相同的源通量水平下,电子等离子体的温度不同,而其他明亮的塞弗特星系在硬X射线下呈现不同的变化模式,光谱变化与通量变化相关(例如NGC 4151)。

英文摘要:

We present preliminary results on the hard X-ray emission properties of the Seyfert 1.5 galaxy MCG+8-11-11 as observed by INTEGRAL and SWIFT. All the INTEGRAL IBIS/ISGRI data available up to October 2009 have been analyzed together with two SWIFT/XRT snapshot observations performed in August and October 2009, quasi-simultaneously to INTEGRAL pointed observations of MCG+8-11-11. No correlation is observed between the hard X-ray flux and the spectral slope, while the position of the high-energy cut-off is found to have varied during the INTEGRAL observations. This points to a change in the temperature of the Comptonising medium from a minimum value of kT = 30-50 keV to values larger than 100-150 keV. There is no significant detection of Compton reflection, with a 3 sigma upper limit of R < 0.2, and no line has been detected at 112 keV, as previously claimed from HEAT observations (112 keV flux F < 2.4e-4 ph/cm^2/s). The variability behaviour of MCG+8-11-11 is found to be similar to that shown by IC 4329A, with different temperatures of the electron plasma for similar flux levels of the source, while other bright Seyfert galaxies present different variability patterns at hard X-rays, with spectral changes correlated to flux variations (e.g. NGC 4151).

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