Radiative Reconnection-powered TeV Flares from the Black Hole Magnetosphere in M87
Radiative Reconnection-powered TeV Flares from the Black Hole Magnetosphere in M87
复制标题
DOI：
10.3847/2041-8213/acb264
复制
发表时间：
2022-09
期刊：
影响因子：
--
通讯作者：
Hayk Hakobyan;B. Ripperda;A. Philippov
中科院分区：
文献类型：
--
作者：
Hayk Hakobyan;B. Ripperda;A. Philippov
总的来说，活动星系核，特别是M87中的超大质量黑洞，都显示出明亮而快速的伽马射线耀斑，能量高达100 GeV或更高。对于M87来说，耀斑表现出多波长成分，其变化时间尺度与视界的动态时间相当，这表明耀斑可能来自核附近的致密区域。然而，这些耀斑的发射机制尚不清楚。最近的高分辨率广义相对论磁流体力学模拟显示，偶发性磁重联事件的发生可以为黑洞事件视界附近的耀斑提供动力。本文从第一性原理出发，分析了适用于M87黑洞的极端等离子体条件下重联电流层的辐射特性。我们表明，在重联层附近预计会产生大量的对，以至于产生的次级对等离子体在重联动力学中占主导地位。利用二维细胞内粒子模拟支持的分析估计，我们证明了在强同步加速器冷却存在的情况下，重连接可以在出射同步加速器（高达几十MeV）和反康普顿信号（高达TeV）中产生对等离子体的硬幂律分布。我们从模拟中生成了合成的辐射光谱，可以直接与未来对M87*耀斑的多波长观测结果进行比较。
Active galactic nuclei in general, and the supermassive black hole in M87 in particular, show bright and rapid gamma-ray flares up to energies of 100 GeV and above. For M87, the flares show multiwavelength components, and the variability timescale is comparable to the dynamical time of the event horizon, suggesting that the emission may come from a compact region near the nucleus. However, the emission mechanism for these flares is not well understood. Recent high-resolution general-relativistic magnetohydrodynamic simulations show the occurrence of episodic magnetic reconnection events that can power flares near the black hole event horizon. In this work, we analyze the radiative properties of the reconnecting current layer under the extreme plasma conditions applicable to the black hole in M87 from first principles. We show that abundant pair production is expected in the vicinity of the reconnection layer, to the extent that the produced secondary pair plasma dominates the reconnection dynamics. Using analytic estimates backed by two-dimensional particle-in-cell simulations, we demonstrate that in the presence of strong synchrotron cooling, reconnection can produce a hard power-law distribution of pair plasma imprinted in the outgoing synchrotron (up to a few tens of MeV) and the inverse-Compton signal (up to TeV). We produce synthetic radiation spectra from our simulations, which can be directly compared with the results of future multiwavelength observations of M87* flares.