arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0909.1017astro-ph.HEastro-ph.SR
收藏

超铝X射线源中的低金属丰度诞生环境和黑洞质量

Low metallicity natal environments and black hole masses in Ultraluminous X-ray Sources

L. Zampieri, T. P. Roberts

摘要:

我们回顾了现有的超亮X射线源(ULXs)中致密天体质量的估计,并批判性地重新考虑了恒星质量与中等质量黑洞的解释。对于大多数ULX来说,不需要几百到几千个$M_\odot$的黑洞,尽管它们可能存在于少数已知的超亮($\sim 10^{41}$ erg s $^{-1}$)物体和/或一些在其功率密度谱中显示定时特征的源中。然而,与此同时,对于低于$\sim 10^{40}$ erg s $^{-1}$的ULX,恒星质量BH可能是一个相当合理的解释,但它们需要超爱丁顿吸积和一些合适的聚束因子对吸积率的依赖关系,以便解释高于这个(各向同性)光度的ULX。我们详细研究了“第三种方式”,其中一部分ULXs包含$\approx 30-90 M_\odot$黑洞在低金属量环境中形成,并在稍微临界的制度中吸积,并发现它可以始终如一地解释明亮ULXs的属性。对ULX位置的调查寻找ULX位置、平均光度和当地金属丰度之间的统计上有意义的关系,将为我们的提议提供一个明确的测试。

英文摘要:

We review the available estimates of the masses of the compact object in Ultraluminous X-ray Sources (ULXs) and critically reconsider the stellar-mass versus intermediate-mass black hole interpretations. Black holes of several hundreds to thousands of $M_\odot$ are not required for the majority of ULXs, although they might be present in the handful of known hyper-luminous ($\sim 10^{41}$ erg s$^{-1}$) objects and/or some sources showing timing features in their power density spectra. At the same time, however, stellar mass BHs may be quite a reasonable explanation for ULXs below $\sim 10^{40}$ erg s$^{-1}$, but they need super-Eddington accretion and some suitable dependence of the beaming factor on the accretion rate in order to account for ULXs above this (isotropic) luminosity. We investigate in detail a 'third way' in which a proportion of ULXs contain $\approx 30-90 M_\odot$ black holes formed in a low metallicity environment and accreting in a slightly critical regime and find that it can consistently account for the properties of bright ULXs. Surveys of ULX locations looking for a statistically meaningful relationship between ULX position, average luminosity and local metallicity will provide a definitive test of our proposal.

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。

↑