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arXiv 1801.05705astro-ph.HEgr-qc
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闪电星的电磁辐射及其对非重复快速射电暴的影响

Electromagnetic emission from blitzars and its impact on non-repeating fast radio bursts

Elias R. Most, Antonios Nathanail, Luciano Rezzolla

摘要:

有人认为,非重复的快速射电暴(FRB)代表了磁化中子星坍缩成黑洞的最终信号。在这个模型中,一颗由快速旋转支撑的超大质量中子星,在诞生后几千到几百万年,由于自旋下降,将坍缩成一个黑洞。坍缩猛烈地折断了锚定在恒星表面的磁场线,从而产生了电磁脉冲,该脉冲将向外传播并加速电子,从而产生大规模的无线电爆发,即“闪电”。我们提出了一个系统的研究旋转和磁化中子星的引力坍缩,特别注意到远场演化后的崩溃。通过考虑一系列中子星的旋转范围从零到毫秒的周期和不同的磁场强度,我们表明,闪电发射是非常强大的,总是由一系列亚毫秒脉冲的振幅呈指数衰减的特点。利用恒星磁场和半径的一个简单表达式,很好地再现了磁层破坏时释放的光度和能量。最后,我们评估的发生对生产过程中的闪电战的情况下,得出的结论是典型的磁场强度的$10^{12}\,{\rm G}$和几赫兹的自旋频率,对生产被抑制。总的来说,模拟结果与通常观察到的FRB的光度之间的非常好的匹配使得闪电模型作为非重复FRB现象的简单而合理的解释具有可信度。

英文摘要:

It has been suggested that a non-repeating fast radio burst (FRB) represents the final signal of a magnetized neutron star collapsing to a black hole. In this model, a supramassive neutron star supported by rapid rotation, will collapse to a black hole several thousand to million years after its birth as a result of spin down. The collapse violently snaps the magnetic-field lines anchored on the stellar surface, thus producing an electromagnetic pulse that will propagate outwards and accelerate electrons producing a massive radio burst, i.e. a "blitzar". We present a systematic study of the gravitational collapse of rotating and magnetised neutron stars with special attention to far-field evolution at late times after the collapse. By considering a series of neutron stars with rotation ranging from zero to millisecond periods and different magnetic-field strengths, we show that the blitzar emission is very robust and always characterised by a series sub-millisecond pulses decaying exponentially in amplitude. The luminosity and energy released when the magnetosphere is destroyed are well reproduced by a simple expression in terms of the stellar magnetic field and radius. Finally, we assess the occurrence of pair production during a blitzar scenario, concluding that for typical magnetic-field strengths of $10^{12}\,{\rm G}$ and spin frequencies of a few Hz, pair production is suppressed. Overall, the very good match between the results of the simulations and the luminosities normally observed for FRBs lends credibility to the blitzar model as a simple and yet plausible explanation for the phenomenology of non-repeating FRBs.

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