Emission of Magnetar Bursts and Precursors of Neutron Star Mergers
Emission of Magnetar Bursts and Precursors of Neutron Star Mergers
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DOI：
10.3847/1538-4357/ac17e7
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发表时间：
2020-11
期刊：
影响因子：
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通讯作者：
A. Beloborodov
中科院分区：
文献类型：
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作者：
A. Beloborodov
磁星爆发可以由在外磁层中增长到非线性振幅δ B/ B = 1的阿尔文波发射，并触发磁重联。类似的磁闪应该准周期性地发生在一个接近合并的磁化中子星星双星中。在这两种情况下，磁耀斑中的快速耗散产生了光学厚度为e ±的等离子体，其热容量与产生的辐射能量相比可以忽略不计。磁耗散则涉及光子粘性，并通过康普顿阻力作用于重联区域中的等离子体体运动。由此产生的康普顿化过程的有效温度是自我调节到几十keV。产生的X射线发射是使用依赖于时间的辐射传输模拟计算的，该模拟遵循e ±对的创建以及光子的产生、康普顿化和逃逸。模拟显示了耗散区如何被穿上e ±涂层，以及逃逸光谱如何通过涂层的辐射传输而成形。结果与观测到的磁星爆发，包括最近的活动SGR 1935+2154伴随着快速无线电爆发进行了比较。对磁化中子星星合并的X射线前兆进行了预测。
Magnetar bursts can be emitted by Alfvén waves growing in the outer magnetosphere to nonlinear amplitudes, δ B/ B ∼ 1, and triggering magnetic reconnection. Similar magnetic flares should occur quasi-periodically in a magnetized neutron star binary nearing merger. In both cases, fast dissipation in the magnetic flare creates optically thick e ± plasma, whose heat capacity is negligible compared with the generated radiation energy. Magnetic dissipation then involves photon viscosity and acts through Compton drag on the plasma bulk motions in the reconnection region. The effective temperature of the resulting Comptonization process is self-regulated to tens of keV. The generated X-ray emission is calculated using time-dependent radiative transfer simulations, which follow the creation of e ± pairs and the production, Comptonization, and escape of photons. The simulations show how the dissipation region becomes dressed in an e ± coat and how the escaping spectrum is shaped by radiative transfer through the coat. The results are compared with observed magnetar bursts, including the recent activity of SGR 1935+2154 accompanied by a fast radio burst. Predictions are made for X-ray precursors of magnetized neutron star mergers.