双星动力学可达性研究
On the dynamical accessibility of twin stars
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中文总结 AI 辅助
本文通过引力束缚能分析和广义相对论流体动力学模拟，发现双星虽在能量上更有利，但需足够快的冷却才能动力学形成，否则中子星更受青睐。
中文摘要 AI 辅助
足够强的强子-夸克一级相变可以产生第三族稳定致密星，通常称为混合强子-夸克星。与中子星具有相同引力质量的稳定混合星被称为双星。尽管平衡态双星可能存在，但它们能否动力学形成仍是一个开放问题。我们通过考察在固定重子静质量下相互竞争的平衡构型的引力束缚能，并对几种可能的转变通道进行广义相对论流体动力学模拟来研究这一问题。虽然双星比具有相同静质量的中子星具有更强的引力束缚，但这种能量偏好本身并不能决定动力学结果。演化过程中的压缩和激波会产生热压力，阻止系统稳定在冷双星分支上。我们的模拟表明，足够快的冷却可以消除这种热支撑并促成双星形成，而较慢或没有冷却通常有利于中子星残骸。通过本文考虑的通道进入双星分支需要冷却时标与恒星动力学时标相当或更短。由于现实冷却机制在更长时标上运行，我们的结果表明，在守恒总静质量的通道中，即使存在具有相同静质量的引力束缚更强的双星构型，中子星也可能在动力学上更受青睐。我们的结果展示了一个原理性结论，至少对于夸克退禁闭密度在温度高达10-20 MeV时变化不大的状态方程而言。
英文摘要
A sufficiently strong hadron-to-quark first-order phase transition can give rise to a third family of stable compact stars that are commonly referred to as hybrid hadron-quark stars. Stable hybrid stars that have the same gravitational mass as neutron stars are referred to as twin stars. Although equilibrium twin stars may exist, whether they can be dynamically formed remains an open question. We investigate this problem by examining the gravitational binding energy of competing equilibrium configurations at fixed baryonic rest mass and by performing general relativistic hydrodynamical simulations of several possible transition channels. While twin stars are more gravitationally bound than neutron stars with the same rest mass, this energetic preference alone does not determine the dynamical outcome. Compression and shocks during the evolution generate thermal pressure that can prevent the system from settling on the cold twin star branch. Our simulations show that sufficiently rapid cooling can remove this thermal support and enable twin star formation, whereas slower or no cooling generally favors a neutron star remnant. Accessing the twin star branch through the formation channels considered here requires cooling on a timescale comparable to or shorter than the stellar dynamical timescale. Since realistic cooling mechanisms operate on much longer timescales, our results suggest that in channels that conserve the total rest-mass neutron stars may be dynamically favored even when a more gravitationally bound twin star configuration exists with the same rest mass. Our results demonstrate a point of principle, at least for equations of state where the quark deconfinement density does not change appreciably for temperatures up to $10-20\,\textrm{MeV}.$
发表机构
- University of Arizona（亚利桑那大学）
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