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arXiv 1910.00554astro-ph.HE
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毫秒磁星的初始演化:一个解析解

The initial evolution of millisecond magnetars: an analytical solution

Sercan Çıkıntoğlu, Sinem Sasmaz Mus, K. Yavuz Ekşi

摘要:

毫秒磁星通常被认为是某些伽马射线暴(GRB)的中心引擎,特别是那些显示出平台阶段的GRB。我们认为,如果初生磁星的磁场处于一个短暂的快速衰减阶段,则可能无法实现明显的平台相。一些缺乏明显平台相的伽玛暴也可能是毫秒磁星的宿主。本文给出了描述同向旋转等离子体存在下中子星的角速度和自转与磁轴倾角演化的耦合方程组的近似解析解。我们还展示了如何解决方案可以推广到不断变化的磁场的情况下。通过贝叶斯分析,对GRB 091018、GRB 070318、GRB 080430、GRB 090618、GRB 110715A、GRB 140206A等6颗可能的磁星的自转周期、倾角、磁偶极矩和制动指数进行了拟合,通过使用我们最近的模型[Eschaummaz Muzen et al. 2019]获得X射线余辉光曲线。我们发现毫秒磁星形成后的第一天内,磁星倾角迅速对准,磁偶极场可能衰减几倍,制动指数变化一个数量级。

英文摘要:

Millisecond magnetars are often invoked as the central engine of some gamma-ray bursts (GRBs), specifically the ones showing a plateau phase. We argue that an apparent plateau phase may not be realized if the magnetic field of the nascent magnetar is in a transient rapid decay stage. Some GRBs that lack a clear plateau phase may also be hosting millisecond magnetars. We present an approximate analytical solution of the coupled set of equations describing the evolution of the angular velocity and the inclination angle between rotation and magnetic axis of a neutron star in the presence of a co-rotating plasma. We also show how the solution can be generalized to the case of evolving magnetic fields. We determine the evolution of the spin period, inclination angle, magnetic dipole moment and braking index of six putative magnetars associated with GRB 091018, GRB 070318, GRB 080430, GRB 090618, GRB 110715A, GRB 140206A through fitting, via Bayesian analysis, the X-ray afterglow light curves by using our recent model [Şaşmaz Muş et al. 2019]. We find that within the first day following the formation of the millisecond magnetar, the inclination angle aligns rapidly, the magnetic dipole field may decay by a few times and the braking index varies by an order of magnitude.

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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