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arXiv 1306.1608astro-ph.HEgr-qc
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双中子星并合形成稳定磁星

Formation of Stable Magnetars from Binary Neutron Star Mergers

Bruno Giacomazzo, Rosalba Perna

摘要:

通过对二元中子星合并进行完全广义相对论磁流体动力学模拟,我们研究了合并的最终结果是稳定磁星的可能性。特别地,我们证明了对于由两个等质量中子星(NS)组成的双星系统,在高密度下,当两个NS的引力质量为引力质量M~1.2 Msun,状态方程与Shen等人的相似时,合并产物是稳定的NS.我们发现这样的NS是差速旋转的,并且是超自旋的,自旋参数J/M^2约为0.86,其中J是它的总角动量,它被一个约为0.1兆太阳的圆盘所包围。虽然在我们的全球模拟中,磁场被放大了大约两个数量级,但局部模拟表明,流体动力学不稳定性和磁旋转不稳定性的开始可能进一步将磁场强度增加到磁星水平。这导致了一个有趣的可能性,对于某些NS合并,一个稳定的磁化NS周围的吸积盘可以形成。我们讨论了这些新的结果的电磁对应物的引力波信号的发射和短伽马射线暴的中央引擎的影响。

英文摘要:

By performing fully general relativistic magnetohydrodynamic simulations of binary neutron star mergers, we investigate the possibility that the end result of the merger is a stable magnetar. In particular, we show that, for a binary composed of two equal-mass neutron stars (NSs) of gravitational mass M~1.2 Msun and equation of state similar to Shen et al. at high densities, the merger product is a stable NS. Such NS is found to be differentially rotating and ultraspinning with spin parameter J/M^2~0.86, where J is its total angular momentum, and it is surrounded by a disk of ~0.1 Msun. While in our global simulations the magnetic field is amplified by about two orders of magnitude, local simulations have shown that hydrodynamic instabilities and the onset of the magnetorotational instability could further increase the magnetic field strength up to magnetar levels. This leads to the interesting possibility that, for some NS mergers, a stable and magnetized NS surrounded by an accretion disk could be formed. We discuss the impact of these new results for the emission of electromagnetic counterparts of gravitational wave signals and for the central engine of short gamma-ray bursts.

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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