Rotational properties of hypermassive neutron stars from binary mergers
Rotational properties of hypermassive neutron stars from binary mergers
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DOI：
10.1103/physrevd.96.043004
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发表时间：
2016-11
影响因子：
5
通讯作者：
M. Hanauske;K. Takami;L. Bovard;L. Rezzolla;J. Font;F. Galeazzi;H. Stocker
中科院分区：
文献类型：
--
作者：
M. Hanauske;K. Takami;L. Bovard;L. Rezzolla;J. Font;F. Galeazzi;H. Stocker
确定双中子星合并或核心坍缩超新星产生的致密天体的微分旋转规律是相对论天体物理学中的一个老问题。解决这个问题很重要，因为它直接影响到这些物体可以达到的最大质量，从而影响到现实条件下黑洞形成的阈值。利用在完全广义相对论中用各种状态和质量方程描述的双中子星合并的大量数值模拟结果，我们研究了由此产生的超大质量中子星的旋转特性。我们发现角速度分布对状态方程只有适度的依赖，从而表现出在孤立和双星系统中致密恒星的其他方面所发现的“准普适”特征。其分布的特征是一个几乎均匀旋转的核心和一个准开普勒“盘”。这种构型与差速旋转恒星平衡模型中通常采用的$j-{\rm constant}$差速旋转定律有很大的不同。此外，包含在这样一个磁盘中的静止质量可以相当大，范围从具有刚性状态方程的高质量二进制的$\simeq 0.03\,M_{\odot}$，到具有软状态方程的低质量二进制的$\simeq 0.2\,M_{\odot}$。我们评论了我们发现的天体物理学意义，以及根据我们的模拟可以推测出的长期进化情景。
Determining the differential-rotation law of compact stellar objects produced in binary neutron stars mergers or core-collapse supernovae is an old problem in relativistic astrophysics. Addressing this problem is important because it impacts directly on the maximum mass these objects can attain and hence on the threshold to black-hole formation under realistic conditions. Using the results from a large number of numerical simulations in full general relativity of binary neutron star mergers described with various equations of state and masses, we study the rotational properties of the resulting hypermassive neutron stars. We find that the angular-velocity distribution shows only a modest dependence on the equation of state, thus exhibiting the traits of "quasi-universality" found in other aspects of compact stars, both isolated and in binary systems. The distributions are characterized by an almost uniformly rotating core and a quasi-Keplerian "disk". Such a configuration is significantly different from the $j-{\rm constant}$ differential-rotation law that is commonly adopted in equilibrium models of differentially rotating stars. Furthermore, the rest-mass contained in such a disk can be quite large, ranging from $\simeq 0.03\,M_{\odot}$ in the case of high-mass binaries with stiff equations of state, up to $\simeq 0.2\,M_{\odot}$ for low-mass binaries with soft equations of state. We comment on the astrophysical implications of our findings and on the long-term evolutionary scenarios that can be conjectured on the basis of our simulations.