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arXiv 1601.02891astro-ph.HE
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高质量X射线双星中中子星自旋降速的探索

Exploration of Spin-down Rate of Neutron Star in High Mass X-ray Binaries

Hai-Lang Dai, Xi-Wei Liu, Xiang-Dong Li

摘要:

基于不同的自旋下降模型,采用演化布居合成方法研究了银河系中风馈中子星(NS)致密($P_{\rm orb}<10$天)高质量X射线双星(HMXB)的统计性质.我们发现,给定\textbf{by assuming that the surrounding material is treated as forming a quasi-static atmosphere}或\textbf{by assuming that the characteristic velocity of matter and the typical Alfv$\acute{e}$n velocity of material in the magnetospheric boundary layer are comparable to the sound speed in the external medium}的超音速螺旋桨阶段的自旋下降速率太低,无法产生所观察到的紧凑HMXB数量。我们还发现,模型建议\textbf{by assuming that the infalling material is ejected with the corotation velocity at the magnetospheric radius when the magnetospheric radius is larger than the corotation radius}和\textbf{by simple integration of the magnetic torque over the magnetosphere}与一个更大的自旋下降率比由\citet{dav81}或\citet{is75}可以预测一个合理的数量观察到的风馈NS紧凑HMXB。通过与观测到的风馈NS紧凑型HMXB在$P_s-P_{orb}$图中的特定分布相比较,我们的计算结果表明亚音速螺旋桨相可能根本不存在。然而,由\citet{wan85,dai06,jia05}建议的自旋下降速率和由\citet{dav73}给出的自旋下降速率似乎都能合理地产生在$P_s-P_{orb}$图中观察到的风馈NS致密HMXB的分布。从我们的计算中,我们找不到哪种自旋下降速率更合理。

英文摘要:

We use the evolutionary population synthesis method to investigate the statistical properties of the wind-fed neutron star (NS) compact ($P_{\rm orb}<10$ days) high-mass X-ray binaries (HMXBs) in our Galaxy, based on different spin-down models. We find that the spin-down rate in the supersonic propeller phase given \textbf{by assuming that the surrounding material is treated as forming a quasi-static atmosphere} or \textbf{by assuming that the characteristic velocity of matter and the typical Alfv$\acute{e}$n velocity of material in the magnetospheric boundary layer are comparable to the sound speed in the external medium} is too low to produce the observed number of compact HMXBs. We also find that the models suggested \textbf{by assuming that the infalling material is ejected with the corotation velocity at the magnetospheric radius when the magnetospheric radius is larger than the corotation radius} and \textbf{by simple integration of the magnetic torque over the magnetosphere} with a larger spin-down rate than that given by \citet{dav81} or \citet{is75} can predict a reasonable number of observed wind-fed NS compact HMXBs. Our calculated results indicate that subsonic propeller phase may not exist at all by comparing with the observed particular distributions of wind-fed NS compact HMXBs in the $P_s-P_{orb}$ diagram. However, the spin-down rate suggested by \citet{wan85,dai06,jia05} and that given by \citet{dav73} both seem reasonable to produce the observed distribution of wind-fed NS compact HMXBs in the $P_s-P_{orb}$ diagram. We cannot find which spin-down rate seems more reasonable from our calculations.

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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