Ultraluminous X-Ray Sources in External Galaxies
Ultraluminous X-Ray Sources in External Galaxies
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DOI：
10.1086/320343
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发表时间：
2001-04
期刊：
影响因子：
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通讯作者：
A. King;M. Davies;M. Ward;G. Fabbiano;M. D. U. O. Leicester;H. C. F. Astrophysics
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文献类型：
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作者：
A. King;M. Davies;M. Ward;G. Fabbiano;M. D. U. O. Leicester;H. C. F. Astrophysics
我们研究了在许多星系中看到的、可能与恒星形成区域有关的超亮非核 X 射线源（即超亮紧凑型 X 射线源 [ULX]）的模型。假设 X 射线发射是各向同性的模型遇到了一些困难。特别是，形成足够数量的所需超大质量黑洞X射线双星是有问题的，并且所得到的系统可能的瞬态行为与观测结果不太相符。相反，温和 X 射线束的假设表明，ULX 可能代表了多种 X 射线双星演化过程中短暂但极为常见的阶段。最好的候选者是热时标质量传递阶段，这在许多中质量和高质量 X 射线双星中是不可避免的。这反过来表明与银河微类星体有联系。高质量 X 射线双星的短暂寿命可以解释 ULX 与恒星形成事件的关联。这些考虑因素仍然允许单个 ULX 可能包含极其巨大的黑洞。
We investigate models for the class of ultraluminous nonnuclear X-ray sources (i.e., ultraluminous compact X-ray sources [ULXs]) seen in a number of galaxies and probably associated with star-forming regions. Models in which the X-ray emission is assumed to be isotropic run into several difficulties. In particular, the formation of sufficient numbers of the required ultramassive black hole X-ray binaries is problematic, and the likely transient behavior of the resulting systems is not in good accord with observation. The assumption of mild X-ray beaming suggests instead that ULXs may represent a short-lived but extremely common stage in the evolution of a wide class of X-ray binaries. The best candidate for this is the phase of thermal-timescale mass transfer that is inevitable in many intermediate- and high-mass X-ray binaries. This in turn suggests a link with the Galactic microquasars. The short lifetimes of high-mass X-ray binaries would explain the association of ULXs with episodes of star formation. These considerations still allow the possibility that individual ULXs may contain extremely massive black holes.