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arXiv 1906.08786astro-ph.HEgr-qc
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准环形差速旋转中子星的动力学稳定性

On the dynamical stability of quasi-toroidal differentially rotating neutron stars

Pedro L. Espino, Vasileios Paschalidis, Thomas W. Baumgarte, Stuart L. Shapiro

摘要:

在完全广义相对论下,通过流体动力学模拟研究了相对论性、微分旋转、准环面中子星模型的动力学稳定性。我们发现,在这项工作中研究的所有准环形配置的动态不稳定的增长的非轴对称模式。单臂和杆模式的不稳定性增长过程中,他们的演变。我们发现,非常高的静止质量配置崩溃形成黑洞。我们的计算表明,配置的静止质量小于二进制中子星的阈值质量迅速坍缩到黑洞动态过渡到球状,差分旋转的动态稳定,但长期不稳定的恒星。我们的研究表明,极端准环形中子星平衡解的存在并不意味着长寿命的二进制中子星合并残留物可以更大的质量比以前发现的。最后,我们发现的模型,最初是超克尔($J/M^2>1$),并经历灾难性的崩溃上的动态时间尺度,在对比发现在早期的作品。然而,宇宙审查在我们所有的情况下都受到尊重。我们的工作明确地表明,超过克尔界的旋转中子星模型并不意味着动力学稳定性。

英文摘要:

We investigate the dynamical stability of relativistic, differentially rotating, quasi-toroidal models of neutron stars through hydrodynamical simulations in full general relativity. We find that all quasi-toroidal configurations studied in this work are dynamically unstable against the growth of non-axisymmetric modes. Both one-arm and bar mode instabilities grow during their evolution. We find that very high rest mass configurations collapse to form black holes. Our calculations suggest that configurations whose rest mass is less than the binary neutron star threshold mass for prompt collapse to black hole transition dynamically to spheroidal, differentially rotating stars that are dynamically stable, but secularly unstable. Our study shows that the existence of extreme quasi-toroidal neutron star equilibrium solutions does not imply that long-lived binary neutron star merger remnants can be much more massive than previously found. Finally, we find models that are initially supra-Kerr ($J/M^2>1$) and undergo catastrophic collapse on a dynamical timescale, in contrast to what was found in earlier works. However, cosmic censorship is respected in all of our cases. Our work explicitly demonstrates that exceeding the Kerr bound in rotating neutron star models does not imply dynamical stability.

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