Title: Optics near Kerr black holes: spectra of advection dominated accretion flows Show Chinese title

Title: 接近Kerr黑洞的光学性质： advective主导的吸积流的光谱

Abstract: We investigate advection dominated, transsonic accretion flows in the vicinity of a Kerr black hole. We take into account all relativistic effects in the dynamics of the flow and in the propagation of light. We assume the matter to be weakly magnetized and cool via the thermal synchrotron and Bremsstrahlung radiation. We include also the effects of Comptonization. We calculate the spectra of radiation as seen by observers located at different positions relative to the equatorial plane of the disk. The radiation emitted by the accreting matter is anisotropic and observers near the equatorial plane register a higher energy flux. This effect is more pronounced in the case of slowly rotating black holes. We calculate also the shape of a hypothetical gamma line, which may be produced by the thermonuclear reactions in the inner part of the flow. The line is strongly broadened, but the fact that the flow is quasi-spherical removes the two-peak shape of the line seen in the spectra emitted from thin, Keplerian disks. The kinematics of the advection dominated flows is not unique (as opposed to Keplerian disks or spherical free-fall) and it would probably be difficult to find strong limits on source models using the spectral observations. Show Chinese abstract

Abstract: 我们研究了接近克尔黑洞的强对流、跨声速吸积流。 我们考虑了流体动力学和光传播中的所有相对论效应。 我们假设物质弱磁化，并通过热同步辐射和布雷玛斯特劳布尔辐射冷却。 我们还考虑了康普顿化效应。 我们计算了相对于盘面不同位置的观察者所观测到的辐射谱。 吸积物质发出的辐射是各向异性的，靠近盘面的观察者记录到更高的能量通量。 对于缓慢旋转的黑洞，这种效应更为显著。 我们还计算了可能由流体内层的热核反应产生的伽马射线线的形状。 该线被强烈展宽，但流体的准球形特性消除了在薄的开普勒盘发射的光谱中看到的双峰线形状。 对流主导的流动动力学并非唯一（与开普勒盘或球形自由落体相反），因此利用光谱观测来对源模型施加严格的限制可能是困难的。