WD2 - Origin and physics of Soft Gamma-ray Repeaters and Anomalous X-ray Pulsars |
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Speaker |
Ikhsanov, Nazar |
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Coauthors |
G.S. Bisnovatyi-Kogan |
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Why periods of AXPs/SGRs are clustered around 2-12 second? |
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Abstract |
We explore a possibility for AXPs and SGRs to be descendants of high-mass X-ray binaries which have been disintegrated in the second supernova explosion. The spin period of neutron stars in high-mass X-ray binaries 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 disk. We show that the expected mass of the disk, 10^-7 - 10^-8 M_sun, 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. References: 1. Bisnovatyi-Kogan and Ikhsanov, Astronomy Reports, 58, 217 (2014) [arXiv:1401.2634v2] 2. Bisnovatyi-Kogan and Ikhsanov, Astronomy Reports, 59, in press (2015) [arXiv:1407.6733v3] |
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