Relating follicly-challenged compact stars to bald black holes: A link between two no-hair properties
Relating follicly-challenged compact stars to bald black holes: A link between two no-hair properties
复制标题
将毛囊受到挑战的致密恒星与秃头黑洞联系起来：两种无毛特性之间的联系
DOI：
10.1103/physrevd.91.103003
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发表时间：
2015
影响因子：
5
通讯作者：
N. Yunes
中科院分区：
文献类型：
--
作者：
Kent Yagi;N. Yunes
致密恒星满足一定的无毛关系，通过这种关系，它们的多极矩由它们的质量、自旋和四极矩给出。这些关系近似地独立于它们的状态方程，即压强与密度的关系。这种关系类似于黑洞无毛定理，但它们拥有事件视界，导致它们形成的信息可以隐藏在视界内。致密恒星没有视界，因此它们的无毛关系是否与黑洞的无毛关系有关尚不清楚。我们通过研究具有各向异性压力的致密恒星的多极矩关系作为一个玩具模型来研究这两种关系是如何联系起来的，这使得这些恒星比具有各向同性压力的恒星更致密。我们在这里用数值表明紧致恒星无毛关系接近黑洞的紧致关系，因为紧致度接近黑洞的紧致关系。我们还分析证明了当强各向异性恒星接近黑洞极限时，电流偶极矩正好在紧致度下二次达到黑洞极限。此外，我们还表明，紧致恒星在这个极限下逐渐变扁，即使由于强各向异性而在低紧致度下延展。
Compact stars satisfy certain no-hair relations through which their multipole moments are given by their mass, spin and quadrupole moment. These relations are approximately independent of their equation of state, relating pressure to density. Such relations are similar to the black hole no-hair theorems, but these possess event horizons inside which information that led to their formation can hide. Compact stars do not possess horizons, so whether their no-hair relations are related to the black hole ones is unclear. We investigate how the two relations are related by studying relations among multipole moments for compact stars with anisotropic pressure as a toy model, which allows such stars to be more compact than those with isotropic pressure. We here show numerically that the compact star no-hair relations approach the black hole ones as the compactness approaches that of a black hole. We also prove analytically that the current dipole moment exactly reaches the black hole limit quadratically in compactness as strongly-anisotropic stars approach the black hole limit. We moreover show that compact stars become progressively oblate in this limit, even if prolate at low compactness due to strong anisotropies.