The brane-world description of our universe entails a large extra dimension and a fundamental scale of gravity that might be lower by several orders of magnitude compared to the Planck scale. An interesting consequence of the brane-world scenario is in the nature of spherically symmetric vacuum solutions to the brane gravitational field equations, with properties quite distinct as compared to the standard black-hole solutions of general relativity. We consider the spherically symmetric accretion of matter onto brane-world black holes in terms of relativistic hydrodynamics by assuming that the inflowing gas obeys a polytropic equation of state. As a first step in this study, we consider the accretion process in an arbitrary static, spherically symmetric space-time, and show that the relativistic equations require a transition to a supersonic flow in the solution. The velocity, temperature, and density profiles are obtained for the case of the polytropic equation of state. We apply the general formalism to the study of the accretion properties of several classes of brane-world black holes, and we obtain the distribution of the main physical parameters of the gas. The astrophysical determination of these physical quantities could discriminate, at least in principle, between the different brane-world models, and place some constraints on the existence of the extra dimensions.
The universal thermodynamic relations between corrections to entropy and extremality for various black holes solutions have been studied. In this regard, we hereby consider a number of different black brane solutions in different structures for perturbative corrections to general relativity. These are, namely, black brane solution in Rastall AdS massive gravity, Einstein-Yang-Mills AdS black brane solution in massive gravity and general anisotropic black brane in Horava-Lifshitz gravity. We calculate both the entropy and extremality bound by introducing a small constant correction to the actio…
Following a recent approach, complete and analytic solutions (brane and bulk) of regular black holes are shown in a brane context. The metrics are regular both on the four-dimensional brane and in the five-dimensional bulk. Like many brane world scenarios, the bulk spacetime is asymptotically anti-de Sitter. On the other hand, a de Sitter core on the brane avoids the singularity inside the event horizon, providing then well-known regular black holes on the brane. From the bulk perspective, the regular black holes are five-dimensional objects, with the event horizon extending to the extra dimen…
It is shown that, in contrast to the case of extreme 4d dilatonic black holes, 4d neutral dilatonic black holes with horizon singularities can not be interpreted as nonsingular nondilatonic black p-branes in (4+p) dimensions, regardless of the number of extra dimensions p. That is, extra dimensions do not remove naked singularities of 4d neutral dilatonic black holes.
Black p-brane Thermodynamics without Constructing Solutions
Center for Joint Quantum Studies, Department of Physics, School of Science, Tianjin University（天津大学理学院物理系联合量子研究中心）；The International Joint Institute of Tianjin University, Fuzhou, Tianjin University（天津大学福州国际联合学院）
我们探讨了在黑洞块中定位膜的可能性。我们明确地研究了BHTZ和Schwarzschild-anti de Sitter（AdS）黑洞的情况。我们的结果是，在这些情况下，膜不能仅仅由膜张力支撑，必须在膜上引入其他形式的物质。我们发现类完美流体的解决方案，遵守特殊的状态方程。对于BHTZ体几何的情况下，状态方程采取的正是一个'' Chaubergin气体''的形式，这是相关的膜上下文。在Schwarzschild-AdS的情况下，我们找到了新的状态方程，当膜位于视界附近时，这些状态方程简化为Chaubergin形式。
In this paper, by taking the accretions into account, the observational shadows and rings casted by the Brane-world black hole are numerically investigated when the observer located at the cosmological horizon. The results here show that the radius $r_p$ of photon sphere increased with cosmological parameter $α$ and dark matter parameter $β$, while the impact parameter $b_p$ decreased with $α$ and increased with $β$. For the thin-disk accretion, it turns out that the total observed intensity are mainly composed of the direct emission, while lensing ring and photon ring only contribute a small …
Can a stationary Bianchi black brane have momentum along the direction with no translational symmetry?
Bianchi黑膜（具有均匀但各向异性的视野的黑膜解，按Bianchi类型分类）提供了一个考虑晶格结构的简单全息设置。在全息超导体的情况下，我们有一个持续的电流与晶格。相应地，我们预期在对偶引力面，黑膜应该沿着晶格结构的方向携带一些动量，在那里平移不变性被破坏。基于这种期望，我们考虑是否-如果可能的话，在什么情况下-一个Bianchi黑膜可以沿着非平移不变性的方向有动量。首先，我们表明，这{ \it不能}的情况下，在Einstein-Maxwell膨胀理论的某类固定Bianchi黑膜解决方案。然后，我们还表明，这{ \it可以}的情况下，一些Bianchi VII $_0$黑膜的数值构造这样一个解决方案，在爱因斯坦-麦克斯韦理论与一个额外的向量场的源项。这个解的视界在视界上具有平移不变性，并传递动量（当紧化时是“旋转的”）。然而，这种平移不变性恰好在视界之外被打破。这表明存在一个黑膜解，它是正则的，但在视界上是非解析的，从而回避了黑洞刚性定理。
In the context of this dissertation, we study the emergence of black-string and black-hole solutions in the framework of five-dimensional braneworld models. The main motivation for studying such theories stems from the Randall-Sundrum model, which was formulated by Lisa Randall and Raman Sundrum back in 1999. We investigate thoroughly the physical characteristics of analytic solutions which concern both black strings and five-dimensional localized black holes. To be more precise, the black-string solutions emerge in the context of a five-dimensional scalar-tensor theory, where the brane line-e…
