Abstract

The optical spectra of ultraluminous X-ray sources (ULXs) show signs of powerful outflows of matter. These outflows are responsible for the formation of a significant portion of optical and ultraviolet emission in ULXs and can either be stellar winds of the donor stars or optically thick outflows (winds) from the surface of supercritical accretion disks. In the latter scenario the outflows are still expected to be similar to stellar winds of massive stars, which allows one to use the same methods for their study based on a comparison of the observed spectra with those simulated within the framework of non-LTE extended atmosphere models. In this paper, we simulate the optical spectrum of the ultraluminous X-ray pulsar NGC 7793 P13, assuming that its emission part is produced in the wind of the supercritical accretion disk. The estimated mass loss rate is about \(1.4\times 10^{-5}M_{\odot}\) yr\({}^{-1}\). We consider the positive and negative aspects of the model and also discuss the applicability of the concept of supercritical disk winds to NGC 7793 P13 and to another well-known ultraluminous X-ray pulsar, NGC 300 ULX-1.

中文翻译：

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NGC 7793 P13 发射光谱的本质：测试超临界吸积盘风模型

摘要

超发光 X 射线源 (ULX) 的光谱显示出物质强烈流出的迹象。这些外流是 ULX 中光学和紫外线发射的很大一部分的形成原因，并且可以是供体恒星的恒星风，也可以是来自超临界吸积盘表面的光学厚外流（风）。在后一种情况下，预计流出量仍将类似于大质量恒星的星风，这使得人们可以根据观测到的光谱与非 LTE 扩展大气框架内模拟的光谱的比较，使用相同的方法进行研究楷模。在本文中，我们模拟了超光度X射线脉冲星NGC 7793 P13的光谱，假设其发射部分是在超临界吸积盘的风中产生的。估计的质量损失率约为\(1.4\times 10^{-5}M_{\odot}\)年\({}^{-1}\)。我们考虑了该模型的积极和消极方面，并讨论了超临界盘风概念对 NGC 7793 P13 和另一个著名的超光度 X 射线脉冲星 NGC 300 ULX-1 的适用性。