论文标题

混合度量 - 帕拉蒂尼重力:黑洞,虫洞,奇异性和不稳定性

Hybrid metric-Palatini gravity: black holes, wormholes, singularities and instabilities

论文作者

Bronnikov, K. A., Bolokhov, S. V., Skvortsova, M. V.

论文摘要

众所周知,T. Harko等人在2012年提出的杂交度量 - 帕拉蒂尼重力理论(HMPG)成功地描述了局部(太阳系系统)和宇宙学观察结果。我们借助于其标量示威表示,讨论了HMPG的静态对称真空溶液。该标量调理与一般相对论与共同耦合的标量场(可以是规范或幻影)相一致,因此该理论的已知解决方案是根据HMPG重新解释的。特别是,在零标量场电位$ v(ϕ)$的情况下,因此里曼尼亚人和帕拉蒂尼ricci标量为零,通用的渐近平面解决方案要么包含裸象象征性,要么描述了可穿越的虫洞,而且只有具有极端水平的黑洞特殊案例。还有一个单参数的解决方案家族,在静态区域之间具有无限数量的极端视野。还描述了具有非零势$ V(ϕ)$的分析解决方案的示例,其中包括具有通用的简单视野的黑洞解决方案,但对于规范标量,它们需要(至少部分)负势。借助幻影标量,有``黑色宇宙''的解决方案将超出地平线的宇宙超越地平线而不是奇异性。在标量单极扰动下,所考虑的大多数解决方案都是不稳定的,但是一些特殊的黑洞解决方案稳定。

The hybrid metric-Palatini theory of gravity (HMPG), proposed in 2012 by T. Harko et al., is known to successfully describe both local (solar-system) and cosmological observations. We discuss static, spherically symmetric vacuum solutions of HMPG with the aid of its scalar-tensor representation. This scalar-tensor theory coincides with general relativity with a conformally coupled scalar field (which can be canonical or phantom), therefore the known solutions of this theory are re-interpreted in terms of HMPG. In particular, in the case of zero scalar field potential $V (ϕ)$, such that both Riemannian and Palatini Ricci scalars are zero, generic asymptotically flat solutions either contain naked singularities or describe traversable wormholes, and there are only special cases of black hole solutions with extremal horizons. There is also a one-parameter family of solutions with an infinite number of extremal horizons between static regions. Examples of analytical solutions with nonzero potentials $V (ϕ)$ are also described, among them black hole solutions with simple horizons which are generic but, for canonical scalars, they require (at least partly) negative potentials. With phantom scalars there are ``black universe'' solutions that lead beyond the horizon to an expanding universe instead of a singularity. Most of the solutions under consideration turn out to be unstable under scalar monopole perturbations, but some special black hole solutions are stable.

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