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arXiv 1407.6733astro-ph.HE
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异常X射线谱的周期聚类

Period clustering of the anomalous X-ray pulsars

G. S. Bisnovatyi-Kogan, N. R. Ikhsanov

摘要:

本文讨论了反常X射线脉冲星(AXP)和软γ射线重复星(SGR)的观测周期为何集中在2-12 s范围内的问题。我们探索了回答这个问题的可能性,假设AXP和SGR是在核心坍缩超新星爆炸中解体的高质量X射线双星(HMXBs)的后代。HMXB中中子星的自旋周期向平衡周期演化,平均约为几秒。在它的大质量伴星爆炸后,中子星被嵌入到一个致密的气体包层中,从中吸积导致形成一个剩余的磁悬浮(ML)盘。我们证明,在这种情况下,盘的预期质量为10^-7 - 10^-8 M_sun,这足以在几千年的时间跨度内维持10^14 - 10^15 g/s的吸积过程。在此期间,恒星表现为一个孤立的X射线脉冲星,其参数与AXP和SGR相似。如果剩余盘的寿命不超过中子星的自旋下降时间尺度,就可以提供这种中子星的周期群集。

英文摘要:

In this paper we address the question of why the observed periods of the Anomalous X-ray Pulsars (AXPs) and Soft Gamma-ray Repeaters (SGRs) are clustered in the range 2-12 s. We explore a possibility to answer this question assuming that AXPs and SGRs are the descendants of High Mass X-ray Binaries (HMXBs) which have been disintegrated in the core-collapse supernova explosion. The spin period of neutron stars in HMXBs evolves towards the equilibrium period, averaging around a few seconds. After the explosion of its massive companion, the neutron star turns out to be embedded into a dense gaseous envelope, the accretion from which leads to the formation of a residual magnetically-levitating (ML) disk. We show that the expected mass of a disk in this case is 10^-7 - 10^-8 M_sun which is sufficient to maintain the process of accretion at the rate 10^14 - 10^15 g/s over a time span of a few thousand years. During this period the star manifests itself as an isolated X-ray pulsar with a number of parameters resembling those of AXPs and SGRs. Period clustering of such pulsars can be provided if the lifetime of the residual disk does not exceed the spin-down timescale of the neutron star.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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