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arXiv 0902.3982astro-ph.HE
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吸积黑洞的X射线偏振:II。热状态

X-ray Polarization from Accreting Black Holes: II. The Thermal State

Jeremy D. Schnittman, Julian H. Krolik

摘要:

利用完全广义相对论下的Monte-Carlo射线追迹方法,计算了黑洞吸积盘在热占优态下的X射线偏振。与许多以前发表的研究相比,我们的方法允许我们包括返回辐射,该辐射被BH的强场引力偏转,并在到达远处的观察者之前从盘上散射。虽然携带相对较小的一部分的总观测通量,散射辐射往往是高度偏振的,并在一个方向垂直于直接辐射。对于中等大的自旋参数(a/M >~ 0.9),这种散射的返回辐射在高于热峰的能量处主导偏振信号,在90度的偏振角中给出净旋转。我们展示了如何从BH在热状态下的偏振光谱的这些新功能可能会发展成为一个强大的工具,用于测量BH自旋和探测气体流在最里面的磁盘。除了确定发射轮廓外,偏振观测还可用于约束系统的其他属性,例如BH质量、倾角和距离。目前正在开发的新工具应该能够在不久的将来利用这一工具。

英文摘要:

We present new calculations of X-ray polarization from black hole (BH) accretion disks in the thermally-dominated state, using a Monte-Carlo ray-tracing code in full general relativity. In contrast to many previously published studies, our approach allows us to include returning radiation that is deflected by the strong-field gravity of the BH and scatters off of the disk before reaching a distant observer. Although carrying a relatively small fraction of the total observed flux, the scattered radiation tends to be highly polarized and in a direction perpendicular to the direct radiation. For moderately large spin parameters (a/M >~ 0.9), this scattered returning radiation dominates the polarization signal at energies above the thermal peak, giving a net rotation in the polarization angle of 90 deg. We show how these new features of the polarization spectra from BHs in the thermal state may be developed into a powerful tool for measuring BH spin and probing the gas flow in the innermost disk. In addition to determining the emission profile, polarization observations can be used to constrain other properties of the system such as BH mass, inclination, and distance. New instruments currently under development should be able to exploit this tool in the near future.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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