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arXiv 1602.09075astro-ph.HE
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关于吸积黑洞的灯柱模型

On the lamppost model of accreting black holes

Andrzej Niedzwiecki, Andrzej A. Zdziarski, Michal Szanecki

摘要:

研究了吸积黑洞系统中X射线源位于靠近视界的旋转轴上的灯柱模型。我们指出了广泛使用的灯柱模型relxillp中的许多不一致之处,例如,忽略了由灯柱发射并直接观察到的光子的红移。它们似乎使那些源距视界的距离在几个引力半径之内的模型拟合结果无效。此外,如果这些结果是正确的,灯柱中产生的大部分光子将被黑洞捕获,并且在无穷远处测量的光源中产生的亮度将比观察到的大得多。这似乎与观察到的X射线双星的硬态和软态之间的平滑状态转换相冲突。所需的增加吸积率和相关的效率降低也提出了一个问题的活动星系核。然后,这些模型意味着在局部框架中测量的亮度要比在源中产生的和在无穷远处测量的亮度高得多,这是由于时间膨胀和红移的附加效应,并且电子温度要明显高于观察到的。我们表明,这些条件意味着拟合源将是对平衡。另一方面,上述问题对距离黑洞较远的源造成了相对较小的问题,在那里relxilllp仍然可以使用。

英文摘要:

We study the lamppost model, in which the X-ray source in accreting black-hole systems is located on the rotation axis close to the horizon. We point out a number of inconsistencies in the widely used lamppost model relxilllp, e.g., the neglect of the redshift of the photons emitted by the lamppost and directly observed. They appear to invalidate those model fitting results for which the source distances from the horizon are within several gravitational radii. Furthermore, if those results were correct, most of the photons produced in the lamppost would be trapped by the black hole, and the luminosity generated in the source as measured at infinity would be much larger than that observed. This appears to be in conflict with the observed smooth state transitions between the hard and soft states of X-ray binaries. The required increase of the accretion rate and the associated efficiency reduction present also a problem for AGNs. Then, those models imply the luminosity measured in the local frame to be much higher than that produced in the source and measured at infinity, due to the additional effects of time dilation and redshift, and the electron temperature to be higher significantly than that observed. We show that these conditions imply that the fitted sources would be out of the pair equilibrium. On the other hand, the above issues pose relatively minor problems for sources at large distances from the black hole, where relxilllp can still be used.

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