Bulk Comptonization by turbulence in accretion discs
Bulk Comptonization by turbulence in accretion discs
复制标题
吸积盘中湍流的整体压缩
DOI：
10.1093/mnras/stw761
复制
发表时间：
2016
影响因子：
4.8
通讯作者：
O. Blaes
中科院分区：
文献类型：
--
作者：
J. Kaufman;O. Blaes
紧致物体周围以辐射压力为主的吸积盘，其湍流速度可能大大超过盘内的电子热速度。因此，在确定涌现谱时，由湍流引起的体混化可能比热混化占优势。无散度湍流引起的体积化仅是由于辐射粘性耗散。它可以通过求解具有等效“波”温度的Kompaneets方程来处理为热复合化，这是湍流级联中每个尺度上存在的功率的加权和。非零散度湍流的体积化是由压力功和辐射粘滞耗散共同作用的结果。在光薄湍流的极限下，压力功对光子光谱的影响可以忽略不计，在此极限下，辐射粘滞耗散可以视为热复合，其温度相当于全湍流功率。在极光厚湍流的极限下，辐射粘性耗散被抑制，局域光子光谱的演化可以用强耦合光子和气体流体的压缩和膨胀来理解。我们讨论了在辐射MHD模拟高亮度吸积流的光谱计算中，这些效应对自一致地解析和解释湍流复合化的影响。
Radiation pressure dominated accretion discs around compact objects may have turbulent velocities that greatly exceed the electron thermal velocities within the disc. Bulk Comptonization by the turbulence may therefore dominate over thermal Comptonization in determining the emergent spectrum. Bulk Comptonization by divergenceless turbulence is due to radiation viscous dissipation only. It can be treated as thermal Comptonization by solving the Kompaneets equation with an equivalent "wave" temperature, which is a weighted sum over the power present at each scale in the turbulent cascade. Bulk Comptonization by turbulence with non-zero divergence is due to both pressure work and radiation viscous dissipation. Pressure work has negligible effect on photon spectra in the limit of optically thin turbulence, and in this limit radiation viscous dissipation alone can be treated as thermal Comptonization with a temperature equivalent to the full turbulent power. In the limit of extremely optically thick turbulence, radiation viscous dissipation is suppressed, and the evolution of local photon spectra can be understood in terms of compression and expansion of the strongly coupled photon and gas fluids. We discuss the consequences of these effects for self-consistently resolving and interpreting turbulent Comptonization in spectral calculations in radiation MHD simulations of high luminosity accretion flows.