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arXiv 1302.5630astro-ph.HE
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超临界吸积吸积盘超亮X射线源:谱能量分布

Ultra-luminous X-ray Sources as Supercritical Accretion Disks: Spectral Energy Distributions

A. Vinokurov, S. Fabrika, K. Atapin

摘要:

本文根据Shakura和Sunyaev的概念,描述了一个超临界吸积盘(SCAD)的光谱能量分布模型。我们将此模型应用于五个超发光X射线源(ULX)。在这种方法中,盘在到中心的距离小于球化半径处变厚,并且温度依赖性为T \propto r ^{-1/2}。在这一区域,盘的光度为L_bol~L_Edd ln(Mdot/Mdot_Edd),并产生强风,在盘的上方形成风漏斗。在球化半径之外,盘是薄的,其总光度为Eddington,L_Edd。薄盘加热从下面吹来的风。从漏斗的内侧,风被超临界盘加热。在本文中,我们不考虑康普顿化的内部热风,必须覆盖深超临界盘区。我们的模型在技术上类似于Gierlinski等人的DISKIR模型。这些模型在磁盘类型(标准-超临界)和辐照(磁盘-风)方面有所不同。我们建议在X射线区域(~0.3 - 1 keV)区分这两种模型,其中SCAD模型具有平坦的nu F_nu谱,而DISKIR模型从不具有平坦部分,因为它是基于标准α盘。这两种模型之间的一个重要区别可以在它们所得到的黑洞质量上找到。在ULX光谱的应用中,DISKIR模型产生的黑洞质量为几百个太阳质量,而SCAD模型产生恒星质量的黑洞~10 M太阳。

英文摘要:

We describe a model of spectral energy distribution in supercritical accretion disks (SCAD) based on the conception by Shakura and Sunyaev. We apply this model to five ultra-luminous X-ray sources (ULXs). In this approach, the disk becomes thick at distances to the center less than the spherization radius, and the temperature dependence is T \propto r^{-1/2}. In this region the disk luminosity is L_bol ~ L_Edd ln(Mdot/Mdot_Edd), and strong wind arises forming a wind funnel above the disk. Outside the spherization radius, the disk is thin and its total luminosity is Eddington, L_Edd. The thin disk heats the wind from below. From the inner side of the funnel the wind is heated by the supercritical disk. In this paper we do not consider Comptonization in the inner hot winds which must cover the deep supercritical disk regions. Our model is technically similar to the DISKIR model of Gierlinski et al. The models differ in disk type (standard - supercritical) and irradiation (disk - wind). We propose to distinguish between these two models in the X-ray region, ~0.3 - 1 keV, where the SCAD model has a flat nu F_nu spectrum, and the DISKIR model never has a flat part, as it is based on the standard alpha-disk. An important difference between the models can be found in their resulting black hole masses. In application to the ULX spectra, the DISKIR model yields black hole masses of a few hundred solar masses, whereas the SCAD model produces stellar-mass black holes ~10 M_sun.

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