Inverse Compton Cooling in the Coronae of Simulated Black Hole Accretion Flows
Inverse Compton Cooling in the Coronae of Simulated Black Hole Accretion Flows
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DOI：
10.3847/1538-4357/abc176
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发表时间：
2020-09
期刊：
影响因子：
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通讯作者：
B. Kinch;S. Noble;J. Schnittman;J. Krolik
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作者：
B. Kinch;S. Noble;J. Schnittman;J. Krolik
我们提出了一个制定的局部冷却功能中使用的扩散，热日冕区域的3D GRMHD模拟吸积黑洞。这种新的冷却功能计算由于逆康普顿散射的冷却速率，考虑在电晕中的每个单元中的相关微观物理和近似的辐射能量密度和康普顿温度，从而整合了从磁盘表面的热种子光子通量。该方法假设离子和电子温度相等（1T）或使用基于实际相关速率方程（库仑和康普顿）的瞬时平衡方法分别计算它们（2T）。该方法被证明是一致的，一个更详细的光线跟踪计算的大部分冷却发生，但执行成本大大降低。作为一个例子，我们将这些方法应用到一个10兆焦耳，非旋转黑洞，在名义上1%的爱丁顿值吸积的harm3d模拟。这种新方法导致辐射效率值超过Novikov-Thorne的65%，与使用原始目标温度冷却函数进行的模拟相比，日冕中的总冷却量更大。时间平均后处理表明，从这些模拟预测的连续谱观测定性类似于实际的X射线双星数据，特别是对于1T方法，与2T版本（Γ = 2.53）相比，它产生更硬的幂律分量（Γ = 2.25）。
We present a formulation for a local cooling function to be employed in the diffuse, hot corona region of 3D GRMHD simulations of accreting black holes. This new cooling function calculates the cooling rate due to inverse Compton scattering by considering the relevant microphysics in each cell in the corona and approximating the radiation energy density and Compton temperature thereby integrating over the thermal seed photon flux from the disk surface. The method either assumes the ion and electron temperatures are equal (1T) or calculates them separately (2T) using an instantaneous equilibrium approach predicated on the actual relevant rate equations (Coulomb and Compton). The method is shown to be consistent with a more detailed ray-tracing calculation where the bulk of the cooling occurs, but is substantially less costly to perform. As an example, we apply these methods to a harm3d simulation of a 10M⊙, non-spinning black hole, accreting at nominally 1% the Eddington value. This new approach leads to radiative efficiency values ≃65% above Novikov–Thorne, with a larger fraction of total cooling in the corona as compared to simulations performed using the original target-temperature cooling function. Time-averaged post-processing reveals that the continuum spectral observations predicted from these simulations are qualitatively similar to actual X-ray binary data, especially so for the 1T approach, which yields a harder power-law component (Γ = 2.25) compared to the 2T version (Γ = 2.53).