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arXiv 2109.01149gr-qcastro-ph.HEhep-th
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四维Einstein-Gauss-Bonnet引力对致密天体的天体物理约束

Astrophysical constraints on compact objects in 4D Einstein-Gauss-Bonnet gravity

Christos Charmousis, Antoine Lehébel, Evangelos Smyrniotis, Nikolaos Stergioulas

摘要:

我们研究了一个特定的四维Horndeski理论起源于高维爱因斯坦-高斯-邦纳引力的紧凑对象的属性。值得注意的是,一个精确的真空解决方案是已知的。这个紧凑的物体与广义相对论的区别主要在于强场区。我们在这个框架下讨论了黑洞的一些性质,并详细研究了静态和慢转的中子星的性质。我们发现,相对温和的偏离广义相对论,在GW 190814的次要对象是兼容的是一个缓慢旋转的中子星,而不诉诸非常僵硬或奇异的状态方程。值得注意的是,中子星的平衡序列与黑洞极限渐近匹配,完全关闭了中子星与相同半径的黑洞之间的质量间隙,尽管平衡解的稳定性尚未确定。因此,中子星序列存在一个与物态方程无关的普适终点。根据我们的结果和目前的观测限制,我们讨论了具体的耦合常数,参数化偏离广义相对论在这个理论的约束。

英文摘要:

We study the properties of compact objects in a particular 4D Horndeski theory originating from higher dimensional Einstein-Gauss-Bonnet gravity. Remarkably, an exact vacuum solution is known. This compact object differs from general relativity mostly in the strong field regime. We discuss some properties of black holes in this framework and investigate in detail the properties of neutron stars, both static and in slow rotation. We find that for relatively modest deviations from general relativity, the secondary object in GW190814 is compatible with being a slowly-rotating neutron star, without resorting to very stiff or exotic equations of state. Remarkably, the equilibrium sequence of neutron stars matches asymptotically to the black hole limit, completetly closing the mass gap between neutron stars and black holes of same radius, although the stability of equilibrium solutions has yet to be determined. As a consequence, there exists a universal endpoint for the neutron star sequence, independent of the equation of state. In light of our results and of current observational constraints, we discuss specific constraints on the coupling constant that parametrizes deviations from general relativity in this theory.

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