Collision of two rotating Hayward black holes

We investigate the spin interaction and the gravitational radiation thermally allowed in a head-on collision of two rotating Hayward black holes. The Hayward black hole is a regular black hole in a modified Einstein equation, and hence it can be an appropriate model to describe the extent to which the regularity effect in the near-horizon region affects the interaction and the radiation. If one black hole is assumed to be considerably smaller than the other, the potential of the spin interaction can be analytically obtained and is dependent on the alignment of angular momenta of the black holes. For the collision of massive black holes, the gravitational radiation is numerically obtained as the upper bound by using the laws of thermodynamics. The effect of the Hayward black hole tends to increase the radiation energy, but we can limit the effect by comparing the radiation energy with the gravitational waves GW150914 and GW151226.     

The Generalized Stefan-Boltzmann Law of Slowly Changing Kerr-Newman Black Hole

Using the entropy density near the event horizon of Kerr-Newman black hole, the instantaneous radiation energy flux and the instantaneous radiation power of the slowly changing Kerr-Newman black hole have been studied. It is found that the thermal radiation of the Kerr-Newman black hole always satisfies the generalized Stefan-Boltzmann law and is affected by the gravitational field, the electromagnetic field around the black hole and the change of black hole event horizon. But the rate of the change of the event horizon usually makes very little affect on the instantaneous radiation energy flux and radiation power. Only when the rate of the change of the event horizon approaches to the light speed, it can make obviously affect on them.     

Instantaneous Radiation Energy Flux and Radiation Power Near the Event Horizon of Slowly Changing Vaidya Black Hole

By the thin film model of the black hole and the assumption of the local thermal equilibrium, the instantaneous radiation energy flux and radiation power of the slowly changing Vaidya black hole have been studied. The result has been obtained that the thermal radiation of the Vaidya black hole satisfies the generalized Stefan-Boltzmann law. When the cut-off distance and the thin film thickness are both fixed, the instantaneous radiation energy flux of the scalar field near the event horizon of the Vaidya black hole is not only related to the black hole mass, but also to the rate of the change of its event horizon and the average effusion velocity of the radiation particles in the thin film. While its instantaneous radiation power is related to the rate of the change of the event horizon and the average radial effusion velocity of the radiation particles in the thin film. These results indicate that the gravitational field around the black hole and the change of its event horizon will both affect the thermal radiation of the black hole.     

Energy and angular momentum flow into a black hole

The area of the event horizon round a rotating black hole will increase in the presence of a non-axisymmetric or time dependent perturbation. If the perturbation is a matter field, the area increase is related to the fluxes of energy and of angular momentum into the black hole in such a way as to maintain the formula for the area in the Kerr solution. For purely gravitational perturbations one cannot define angular momentum locally but one can use the area increase and the expression for area in terms of mass and angular momentum to calculate the slowing down of a black hole caused by a non-axisymmetric distribution of matter at a distance. It seems that the coupling between the rotation of a black hole and the orbit of a particle going round it can be significant if the angular momentum of the black hole is close to its maximum possible value and if the angular velocity of the particle is nearly equal to that of the black hole.Alfred P. Sloan Research Fellow, supported in part by the National Science Foundation.     

Reissner-Nordstrom黑洞中带电粒子由隧穿导致的Hawking辐射的进一步讨论

以Reissner-Nordstrom黑洞(R-N黑洞)为例，从黑洞热力学定律出发，对R-N黑洞中的带电粒子的量子隧穿效应进行了重新分析.将作用量的虚部重写成黑洞热力学定律的形式后，发现在Parikh工作框架下的量子隧穿效应与黑洞热力学的第一、第二定律有潜在的联系；而且，如果认为量子隧穿过程为可逆过程，则量子隧穿效应中的结果与黑洞热力学第一、第二定律是一致的.换而言之，Parikh的结论只对可逆过程成立. 关键词： Reissner-Nordstrom黑洞 黑洞热力学定律 隧穿 可逆过程     

Black holes in the Brans-Dicke

It is shown that a stationary space containing a black hole is a solution of the Brans-Dicke field equations if and only if it is a solution of the Einstein field equations. This implies that when the star collapses to form a black hole, it loses that fraction (about 7%) of its measured gravitational mass that arises from the scalar interaction. This mass loss is in addition to that caused by emission of scalar or tensor gravitational radiation. Another consequence is that there will not be any scalar gravitational radiation emitted when two black holes collide.     

Gravitational radiation from an extreme Kerr black hole

We analytically investigate gravitational radiation induced by a test particle falling into an extreme Kerr black hole. Assuming the radiation is dominated by the infinite sequence of quasi-normal modes which has the limiting frequencym/(2M), wherem is an azimuthal eigenvalue andM is the mass of the black hole. we find the radiated energy diverges logarithmically in time. Then we evaluate the back reaction to the black hole by appealing to the energy and angular momentum conservation laws. We find the radiation has a tendency to increase the ratio of the angular momentum to mass of the black hole, which is completely different from the non-extreme case, while the contribution of the test particle is to decrease it.     

球对称动态黑洞视界附近的瞬时辐射能通量及瞬时辐射功率

采用黑洞的薄膜模型和局域热平衡的假定,研究球对称动态黑洞视界附近的瞬时辐射能通量和瞬时辐射功率,得到了当截断距离η取定后,Vaidya黑洞视界附近标量场的瞬时辐射能通量与黑洞的质量和视界变化率有关,其瞬时辐射功率仅与黑洞的视界变化率有关.Vaidya-Bonner黑洞的瞬时辐射能通量和瞬时辐射功率与黑洞的质量、电荷和视界变化率有关.表明黑洞周围的引力场、电磁场以及视界的变化均对黑洞的热辐射产生影响.     

The thermal radiation from dynamic black holes

Using the related formula of dynamic black holes, the instantaneous radiation energy density of the general spherically symmetric charged dynamic black hole and the arbitrarily accelerating charged dynamic black hole is calculated. It is found that the instantaneous radiation energy density of black hole is always proportional to the quartic of the temperature of event horizon in the same direction. The proportional coefficient of generalized Stefan-Boltzmann is no longer a constant, and it becomes a dynamic coefficient that is related to the event horizon changing rate, space-time structure near event horizon and the radiation absorption coefficient of the black hole. It is shown that there should be an internal relation between the gravitational field around black hole and its thermal radiation. Supported by the Science Foundation of Heze University (Grant No. XY06WL01)     

The generalized Stefan--Boltzmann law of a rectilinear non-uniformly accelerating Kinnersley black hole

Using entropy density of Dirac field near the event horizon of a rectilinear non-uniformly accelerating Kinnersley black hole, the law for the thermal radiation of black hole is studied and the instantaneous radiation energy density is obtained. It is found that the instantaneous radiation energy density of a black hole is always proportional to the quartic of the temperature on event horizon in the same direction. That is to say, the thermal radiation of a black hole always satisfies the generalized Stefan--Boltzmann law. In addition, the derived generalized Stefan--Boltzmann coefficient is no longer a constant, but a dynamic coefficient related to the space--time metric near the event horizon and the changing rate of the event horizon in black holes.     

Letter: The Gravitational Energy of a Black Hole

An exact energy expression for a physical black hole is derived by considering the escape of a photon from the black hole. The mass of the black hole within its horizon is found to be twice its mass as observed at infinity. This result is important in understanding gravitational waves in black hole collisions.     

Analytic solutions in the dyon black hole with a cosmic string: Scalar fields,Hawking radiation and energy flux

Charged massive scalar fields are considered in the gravitational and electromagnetic field produced by a dyonic black hole with a cosmic string along its axis of symmetry. Exact solutions of both angular and radial parts of the covariant Klein–Gordon equation in this background are obtained, and are given in terms of the confluent Heun functions. The role of the presence of the cosmic string in these solutions is showed up. From the radial solution, we obtain the exact wave solutions near the exterior horizon of the black hole, and discuss the Hawking radiation spectrum and the energy flux.     

Entanglement system,Casimir energy and black hole

We investigate the connection between the entanglement system in Minkowski spacetime and the black hole using the scaling analysis. Here we show that the entanglement system satisfies the Bekenstein entropy bound. Even though the entropies of two systems are the same form, the entanglement energy is different from the black hole energy. Introducing the Casimir energy of the vacuum energy fluctuations rather than the entanglement energy, it shows a feature of the black hole energy. Hence the Casimir energy is more close to the black hole than the entanglement energy. Finally, we find that the entanglement system behaves like the black hole if the gravitational effects are included properly.     

Black hole thermodynamics and the factor of 2 problem

We show that the recent tunneling formulas for black hole radiation in static, spherically symmetric spacetimes follow as a consequence of the first law of black hole thermodynamics and the area-entropy relation based on the radiation temperature. A tunneling formula results even if the radiation temperature is different from the one originally derived by Hawking and this is discussed in the context of the recent factor of 2 problem. In particular, it is shown that if the radiation temperature is higher than the Hawking temperature by a factor of two, thermodynamics then leads to a tunneling formula which is exactly the one recently found to be canonically invariant.     

Towers of gravitational theories

In this essay we introduce a theoretical framework designed to describe black hole dynamics. The difficulties in understanding such dynamics stems from the proliferation of scales involved when one attempts to simultaneously describe all of the relevant dynamical degrees of freedom. These range from the modes that describe the black hole horizon, which are responsible for dissipative effects, to the long wavelength gravitational radiation that drains mechanical energy from macroscopic black hole bound states. We approach the problem from a Wilsonian point of view, by building a tower of theories of gravity each of which is valid at different scales. The methodology leads to multiple new results in diverse topics including phase transitions of Kaluza-Klein black holes and the interactions of spinning black hole in non-relativistic orbits. Moreover, our methods tie together speculative ideas regarding dualities for black hole horizons to real physical measurements in gravitational wave detectors.     

带有电荷、磁荷的一类任意加速黑洞的瞬时辐射能通量

利用带有电荷、磁荷的一类任意加速黑洞视界面附近标量场的熵密度,研究黑洞的热辐射规律,导出了黑洞的瞬时辐射能通量,得到了黑洞的热辐射总是满足广义Stefan-Boltzmann定律的结论.导出的广义Stefan-Boltzmann系数不是常数,而是一个与黑洞参量(质量、所带的电荷与磁荷、加速度的大小、视界的变化率)有关的动比例系数.对于不同的动态黑洞,由于黑洞周围的引力场和电磁场不同,导出的广义Stefan-Boltzmann系数也不同.     

动态球对称Einstein-Yang-Mills-Chern-Simons黑洞的霍金辐射

用Hamilton-Jacobi方法研究了动态球对称Einstein-Yang-Mills-Chern-Simons 黑洞事件视界处的隧穿辐射特征及其黑洞事件视界处的温度. 其结果表明,黑洞温度及隧穿率与黑洞的固有性质及其动态特征有关. 这对于进一步研究动态黑洞的热力学性质及其相关问题是有意义的. 其方法的重要意义在于研究这类动态黑洞的霍金辐射时, 不仅适用于标量场隧穿辐射的情形, 同时也适用于研究旋量场、矢量场以及引力波的隧穿辐射. 关键词： Einstein-Yang-Mills-Chern-Simons黑洞 霍金隧穿辐射 Hamilton-Jacobi方程     

An interpretation for the entropy of a black hole

We investigate the meaning of the entropy carried away by Hawking radiations from a black hole. We propose that the entropy for a black hole measures the uncertainty of the information about the black hole forming matter’s precollapsed configurations, self-collapsed configurations, and inter-collapsed configurations. We find that gravitational wave or gravitational radiation alone cannot carry all information about the processes of black hole coalescence and collapse, while the total information locked in the hole could be carried away completely by Hawking radiation as tunneling.     

Radiation energy flux of Dirac field of static spherically symmetric black holes

By the statistical entropy of the Dirac field of the static spherically symmetric black hole, the result is obtained that the radiation energy flux of the black hole is proportional to the quartic of the temperature of its event horizon. That is, the thermal radiation of the black hole always satisfies the generalised Stenfan--Boltzmann law. The derived generalised Stenfan--Boltzmann coefficient is no longer a constant. When the cut-off distance and the thin film thickness are both fixed, it is a proportional coefficient related to the space--time metric near the event horizon and the average radial effusion velocity of the radiation particles from the thin film. Finally, the radiation energy fluxes and the radiation powers of the Schwarzschild black hole and the Reissner--Nordstrõm black hole are derived, separately.