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arXiv 2109.07657astro-ph.HEgr-qc
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在吸积毫秒X射线天体中模拟自旋上升事件

Modelling spin-up episodes in accreting millisecond X-ray pulsars

Kostas Glampedakis, Arthur G. Suvorov

摘要:

吸积毫秒X射线谱仪在其连续的爆发和静止状态期间提供了丰富的物理信息。根据观测到的这些天体的自旋上升和下降速率,除其他外,有可能推断恒星的磁场强度和吸积盘流的测试模型。在本文中,我们认为三个吸积X射线天体(XTE J1751-305,IGR J 00291 +5934,和SAX J1808.4-3658)与最好的时间数据,并建立模型的帮助下,收集的标准扭矩模型,描述了一个磁螺纹吸积盘截断在磁层半径观察到的自旋上升率。虽然这些模型都不能解释的观测数据,我们发现,列入物理动机的唯象参数$ξ$,它控制的磁层半径的位置的不确定性,导致增强光盘集成吸积扭矩。这些“新的”扭矩模型与观测到的自旋上升率以及推断出的这些物体的磁场是兼容的,前提是$ξ\approx 0.1-0.5$。我们的研究结果补充了额外的物理效应,包括多极磁场和广义相对论引力的存在下的相关性的讨论。

英文摘要:

Accreting millisecond X-ray pulsars are known to provide a wealth of physical information during their successive states of outburst and quiescence. Based on the observed spin-up and spin-down rates of these objects it is possible, among other things, to infer the stellar magnetic field strength and test models of accretion disc flow. In this paper we consider the three accreting X-ray pulsars (XTE J1751-305, IGR J00291+5934, and SAX J1808.4-3658) with the best available timing data, and model their observed spin-up rates with the help of a collection of standard torque models that describe a magnetically-threaded accretion disc truncated at the magnetospheric radius. Whilst none of these models are able to explain the observational data, we find that the inclusion of the physically motivated phenomenological parameter $ξ$, which controls the uncertainty in the location of the magnetospheric radius, leads to an enhanced disc-integrated accretion torque. These 'new' torque models are compatible with the observed spin-up rates as well as the inferred magnetic fields of these objects provided that $ξ\approx 0.1-0.5$. Our results are supplemented with a discussion of the relevance of additional physics effects that include the presence of a multipolar magnetic field and general-relativistic gravity.

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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