标题： 具有氦星 companions 的超亮 X 射线源 显示英文标题

标题： Ultraluminous X-ray sources with He star companions

摘要： 超亮X射线源（ULXs）是非核点状天体，观测到它们具有极高的X射线亮度，超过了$\rm10\,M_\odot$黑洞的爱丁顿极限。 由于发现其X射线脉动现象，一部分ULXs被确认包含中子星（NS）吸积盘。 由于观测偏差，NS ULXs中探测到的供体通常是明亮的大质量恒星。 最近，在NGC 247 ULX-1中识别出了氦供体星，这是ULXs中氦供体星的第一个证据。 本文使用恒星演化代码MESA研究了通过NS+氦星通道形成ULXs的过程，在该过程中，氦星通过洛希瓣溢流将其富含氦的物质转移到中子星表面。 我们演化了大量的NS+氦星系统，并提供了ULXs产生的参数空间。 我们发现，产生ULXs的初始NS+氦星系统应具有$\rm\sim 0.7-2.6 \, M_\odot$的氦星和$\rm \sim 0.1-2500\, d$的轨道周期，最终演化为中间质量双星脉冲星。 根据双星群体合成计算，我们估计银河系中具有氦供体星的NS ULXs的发生率为$\sim1.6-4.0\times10^{-4}\,{\rm yr}^{-1}$，且银河系中存在$\sim7-20$个可检测的具有氦供体星的NS ULXs。 显示英文摘要

摘要： Ultraluminous X-ray sources (ULXs) are non-nuclear point-like objects observed with extremely high X-ray luminosity that exceeds the Eddington limit of a $\rm10\,M_\odot$ black hole. A fraction of ULXs has been confirmed to contain neutron star (NS) accretors due to the discovery of their X-ray pulsations. The donors detected in NS ULXs are usually luminous massive stars because of the observational biases. Recently, the He donor star in NGC 247 ULX-1 has been identified, which is the first evidence of a He donor star in ULXs. In this paper, we employed the stellar evolution code MESA to investigate the formation of ULXs through the NS+He star channel, in which a He star transfers its He-rich material onto the surface of a NS via Roche-lobe overflow. We evolved a large number of NS+He star systems and provided the parameter space for the production of ULXs. We found that the initial NS+He star systems should have $\rm\sim 0.7-2.6 \, M_\odot$ He star and $\rm \sim 0.1-2500\, d$ orbital period for producing ULXs, eventually evolving into intermediate-mass binary pulsars. According to binary population synthesis calculations, we estimated that the Galactic rate of NS ULXs with He donor stars is in the range of $\sim1.6-4.0\times10^{-4}\,{\rm yr}^{-1}$, and that there exist $\sim7-20$ detectable NS ULXs with He donor stars in the Galaxy.