发表机构
Komazawa University; University of Tsukuba; Institute of Science Tokyo; The University of Tokyo; RIST, Kobe（驹泽大学; 筑波大学; 东京科学大学; 东京大学; 神户科学技术研究院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过广义相对论辐射磁流体动力学模拟发现，克尔黑洞周围高自旋MAD超临界吸积流中，电磁能耗散可将辐射效率提升至0.60，有效俘获半径缩小至2.5r_g，磁通量是影响超临界吸积流辐射特性的关键因素。
AI 中文摘要
我们研究黑洞自旋和磁通量大小如何影响超临界吸积流中的电磁能耗散与辐射输运。为此，我们对具有不同黑洞自旋的MAD（磁化吸积盘）和SANE（标准及正常演化吸积）吸积流开展了广义相对论辐射磁流体动力学模拟。在高自旋MAD模型中，我们发现，通过Blandford-Znajek机制提取的一部分电磁能会在黑洞附近的吸积盘表面附近耗散，这种耗散对辐射能的产生有显著贡献并提升了光度。时间平均辐射效率达到η_rad=0.60，远大于无自旋黑洞情况的0.088以及对应SANE状态的弱磁通量情况的0.21。由此，有效俘获半径（定义为向外辐射光度等于向内辐射光度的半径）为r_trap=2.5r_g，与最内稳定圆轨道（ISCO）半径相当，该值显著小于无自旋情况的12r_g和SANE状态的8.5r_g。这些结果表明，黑洞上积累的磁通量大小会影响超临界吸积流的辐射特性，因此在解释观测到的光度和光谱时，除黑洞质量、自旋和吸积率外，还应考虑这一因素。
英文摘要
We investigate how black hole spin and the amount of magnetic flux affect electromagnetic energy dissipation and radiation transport in supercritical accretion flows. For this purpose, we perform general relativistic radiation magnetohydrodynamic simulations of MAD and SANE accretion flows with different black hole spins. In the high-spin MAD model, we find that a fraction of the electromagnetic energy extracted by the Blandford--Znajek mechanism is dissipated near the disk surface in the vicinity of the black hole. This dissipation significantly contributes to the generation of radiative energy and enhances the luminosity. The time-averaged radiative efficiency reaches $η_{\rm rad}=0.60$, which is much larger than $0.088$ for the non-spinning black hole case and $0.21$ for the weak-magnetic-flux case, corresponding to the SANE state. As a result, the effective trapping radius, defined as the radius at which the outward radiative luminosity becomes equal to the inward radiative luminosity, is $r_{\rm trap}=2.5r_{\rm g}$, comparable to the ISCO radius. This value is significantly smaller than $12r_{\rm g}$ for the non-spinning case and $8.5r_{\rm g}$ for the SANE state. These results suggest that the amount of magnetic flux accumulated on the black hole can affect the radiative properties of supercritical accretion flows and should therefore be considered, in addition to black hole mass, spin, and mass accretion rate, when interpreting observed luminosities and spectra.
Comments18 pages, 10 figures, 1 table. Accepted for publication in ApJ
