Searching for dynamical black holes in various theories of gravity
Searching for dynamical black holes in various theories of gravity
复制标题
DOI：
10.1103/physrevd.103.044055
复制
发表时间：
2020-10
影响因子：
5
通讯作者：
S. Nojiri;S. Odintsov;V. Faraoni
中科院分区：
文献类型：
--
作者：
S. Nojiri;S. Odintsov;V. Faraoni
我们构造了具有两个标量场的爱因斯坦引力和$f(R)$引力模型，该模型承认描述时变动力学黑洞的解析解。在绝热近似下研究了它们的热力学。除了Misner-Sharp-Hernandez准局部质量外，我们还提供了随时间变化的热力学量，包括霍金温度、亥姆霍兹自由能、熵和热力学能。后者并不总是与视界上的Misner-Sharp-Hernandez质量重合，尽管它们在静态极限上重合。对于爱因斯坦引力中的史瓦西型（即${g}_{tt}{g}_{rr}=\ensuremath{-}1$）黑洞，两个标量中的一个总是具有负动能的幽灵。我们证明在f(R)重力中可以避免这种鬼影。
We construct models of Einstein and $f(R)$ gravity with two scalar fields, which admit analytical solutions describing time-varying dynamical black holes. Their thermodynamics is investigated in the adiabatic approximation. In addition to the Misner-Sharp-Hernandez quasilocal mass, we provide time-dependent thermodynamical quantities, including the Hawking temperature, Helmholtz free energy, entropy, and thermodynamical energy. The latter does not always coincide with the Misner-Sharp-Hernandez mass at the horizon, although they coincide in the static limit. For Schwarzschild-type (i.e., ${g}_{tt}{g}_{rr}=\ensuremath{-}1$) black holes in Einstein gravity, one of the two scalars is always a ghost with negative kinetic energy. We show that this ghost can be avoided in $f(R)$ gravity.