标题： S2星作为研究人马座A*吸积盘的探针 显示英文标题

标题： The S2 star as a probe of the accretion disk of Sgr A*

摘要： 围绕银河系中心的超大质量黑洞以及其它高度亚爱丁顿吸积体的吸积过程仍然了解不足。 银河系中心S2恒星的轨道穿过超大质量黑洞的吸积盘，这种相互作用的任何观测特征可能被用作吸积探测手段。 由于其早期恒星类型，S2预计会拥有一个相当强大的风。 我们在这里显示，吸积盘的动压在恒星附近相当近的地方冲击恒星风。 受冲击的流体达到约1 keV的温度，并通过光学薄的热轫致辐射发射有效冷却。 受冲击恒星风的辐射在恒星近日点通过时期达到峰值，其光度可能与从人马座A*检测到的宁静发射相当。 探测受冲击恒星风的辐射可以限制黑洞数千个引力半径距离处的吸积盘密度。 显示英文摘要

摘要： How accretion proceeds around the massive black hole in the Galactic center and other highly sub-Eddington accretors remains poorly understood. The orbit of the S2 star in the Galactic center passes through the accretion disk of the massive black hole and any observational signature from such interaction may be used as an accretion probe. Because of its early stellar type, S2 is expected to possess a fairly powerful wind. We show here that the ram pressure of the accretion disk shocks the stellar wind fairly close to the star. The shocked fluid reaches a temperature of ~ 1 keV and cools efficiently through optically thin, thermal bremsstrahlung emission. The radiation from the shocked wind peaks around the epoch of the pericenter passage of the star at a luminosity potentially comparable to the quiescent emission detected from Sgr A*. Detection of shocked wind radiation can constrain the density of the accretion disk at a distance of several thousands of gravitational radii from the black hole.