Bremsstrahlung in GRMHD Models of Accreting Black Holes
Bremsstrahlung in GRMHD Models of Accreting Black Holes
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DOI：
10.3847/1538-4357/ab9808
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发表时间：
2020-06
期刊：
影响因子：
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通讯作者：
R. Yarza;G. Wong;B. Ryan;C. Gammie
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文献类型：
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作者：
R. Yarza;G. Wong;B. Ryan;C. Gammie
韧致辐射在缓慢吸积的超大质量黑洞周围热吸积流的辐射中的作用还没有被完全理解。为了评价轫致辐射相对于其他辐射过程的重要性，我们计算了缓慢吸积超大质量黑洞周围吸积盘的光谱能量分布，包括同步辐射、逆康普顿散射和轫致辐射。我们计算SED（i）四个轴对称辐射广义相对论磁流体力学（RadGRMHD）模拟的108 M的黑洞吸积率之间，（ii）四个轴对称RadGRMHD模拟的M87* 与不同的无量纲自旋a* 和黑洞质量，和（iii）一个三维GRMHD模拟缩放为Sgr A*。在，大部分的光度是同步辐射，而在三个辐射过程有相似的光度。在大多数模型中，韧致辐射在512 keV附近占主导地位。在M87* 模型中，如果a* = 0.5，则韧致辐射主导SED的这一部分，但是如果a* = 0.9375，则逆康普顿散射主导。由于散射比韧致辐射更易变，这一结果表明，512 keV的变化可能是黑洞自旋的诊断。在附录中，我们比较了文献中的一些韧致辐射公式。
The role of bremsstrahlung in the emission from hot accretion flows around slowly accreting supermassive black holes is not thoroughly understood. In order to appraise the importance of bremsstrahlung relative to other radiative processes, we compute spectral energy distributions (SEDs) of accretion disks around slowly accreting supermassive black holes including synchrotron radiation, inverse Compton scattering, and bremsstrahlung. We compute SEDs for (i) four axisymmetric radiative general relativistic magnetohydrodynamics (RadGRMHD) simulations of 108M⊙ black holes with accretion rates between and , (ii) four axisymmetric RadGRMHD simulations of M87* with varying dimensionless spin a* and black hole mass, and (iii) a 3D GRMHD simulation scaled for Sgr A*. At , most of the luminosity is synchrotron radiation, while at the three radiative processes have similar luminosities. In most models, bremsstrahlung dominates the SED near 512 keV. In the M87* models, bremsstrahlung dominates this part of the SED if a* = 0.5, but inverse Compton scattering dominates if a* = 0.9375. Since scattering is more variable than bremsstrahlung, this result suggests that 512 keV variability could be a diagnostic of black hole spin. In the Appendix, we compare some bremsstrahlung formulae found in the literature.