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1.
A stationary solution of the Dirac equation in the metric of a Reissner-Nordström black hole has been found. Only one stationary regular state outside the black hole event horizon and only one stationary regular state below the Cauchy horizon are shown to exist. The normalization integral of the wave functions diverges on both horizons if the black hole is non-extremal. This means that the solution found can be only the asymptotic limit of a nonstationary solution. In contrast, in the case of an extremal black hole, the normalization integral is finite and the stationary regular solution is physically self-consistent. The existence of quantum levels below the Cauchy horizon can affect the final stage of Hawking black hole evaporation and opens up the fundamental possibility of investigating the internal structure of black holes using quantum tunneling between external and internal states. 相似文献
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In 4-dimensional General Relativity, there are several theorems restricting the topology of the event horizon of a black hole. In the stationary case, black holes must have a spherical horizon, while a toroidal spatial topology is allowed only for a short time. In this Letter, we consider spinning black holes inspired by Loop Quantum Gravity and by alternative theories of gravity. We show that the spatial topology of the event horizon of these objects changes when the spin parameter exceeds a critical value and we argue that the phenomenon may be quite common for non-Kerr black holes. Such a possibility may be relevant in astrophysics, as in some models the accretion process can induce the topology transition of the horizon. 相似文献
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Ren Zhao Li-Chun Zhang Yue-Qin Wu Huai-Fan Li 《International Journal of Theoretical Physics》2011,50(1):244-250
We investigate the temperature and energy on holographic screens for 4-dimensional axisymmetric black holes with the entropic
force idea proposed by Verlinde. According to the principle of thermal equilibrium, the location of holographic screen outside
the axisymmetric black hole horizon is not a equivalent radius surface. The location of isothermal holographic screen outside
the axisymmetric black hole horizon is obtained. Using the equipartition rule, we derive the correction expression of energy
of isothermal holographic screen. When holographic screens are far away the black hole horizon, the entropic force of charged
rotating particles can be expressed as Newton’s law of gravity. When the screen crosses the event horizon, the temperature
of the screen agrees with the Hawking temperature and the entropic force gives rise to the surface gravity for both of the
black holes. 相似文献
5.
All known stationary black hole solutions in higher dimensions possess additional rotational symmetries in addition to the
stationary Killing field. Also, for all known stationary solutions, the event horizon is a Killing horizon, and the surface
gravity is constant. In the case of non-degenerate horizons (non-extremal black holes), a general theorem was previously established
[24] proving that these statements are in fact generally true under the assumption that the spacetime is analytic, and that
the metric satisfies Einstein’s equation. Here, we extend the analysis to the case of degenerate (extremal) black holes. It
is shown that the theorem still holds true if the vector of angular velocities of the horizon satisfies a certain “diophantine
condition,” which holds except for a set of measure zero. 相似文献
6.
Particle creation by black holes 总被引:42,自引:0,他引:42
S. W. Hawking 《Communications in Mathematical Physics》1975,43(3):199-220
In the classical theory black holes can only absorb and not emit particles. However it is shown that quantum mechanical effects
cause black holes to create and emit particles as if they were hot bodies with temperature
where κ is the surface gravity of the black hole. This thermal emission leads to a slow decrease in the mass of the black
hole and to its eventual disappearance: any primordial black hole of mass less than about 1015 g would have evaporated by now. Although these quantum effects violate the classical law that the area of the event horizon
of a black hole cannot decrease, there remains a Generalized Second Law:S+1/4A never decreases whereS is the entropy of matter outside black holes andA is the sum of the surface areas of the event horizons. This shows that gravitational collapse converts the baryons and leptons
in the collapsing body into entropy. It is tempting to speculate that this might be the reason why the Universe contains so
much entropy per baryon. 相似文献
7.
Quantum Thermal Effect of Nonstationary Kerr-Newman Black Hole 总被引:4,自引:0,他引:4
The Hawking radiation and the entropy of non-stationary Kerr-Newman black hole whose metric changes slowly are calculated via the method of Damour etc. and the thin film brick-wall model. First, we obtain the Hawking radiation temperature and the thermal spectrum formula. Second, we get the entropy density at every point of the horizon surface as well as the total entropy of the black hole, which is just the Bekenstein-Hawking entropy and relies on the notion of the local equilibrium crucially that can be met if the evaporation and the accretion of the black hole is negligible. The results show that the temperature of the event horizon depends on the time and the angle, and the entropy of the non-stationary black hole is also proportional to the horizon area with appropriate cutoff relationship as in the case of stationary black holes. 相似文献
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本文给出了Kerr-NUT黑洞视界高斯曲率的解析表达式,分析了NUT参数对视界的赤道周长和极向周长的影响,研究了将其视界嵌入欧几里得空间的问题。结果表明这种黑洞的视界具有其它黑洞所没有的几何性质。
关键词: 相似文献
10.
《中国科学:物理学 力学 天文学(英文版)》2021,(6)
The destruction of a regular black hole event horizon might provide us the possibility to access regions inside black hole event horizon. This paper investigates the possibility of overcharging a charged Taub-NUT regular black hole via the scattering of a charged field and the absorption of a charged particle. For the charged scalar field scattering, both the near-extremal and extremal charged Taub-NUT regular black holes cannot be overcharged. For the test charged particle absorption, the result shows that the event horizon of the extremal charged Taub-NUT regular black hole still exists while the event horizon of the near-extremal one can be destroyed. However, if the charge and energy cross the event horizon in a continuous path, the near-extremal charged Taub-NUT regular black hole might not be overcharged. 相似文献
11.
The gravitational collapse of a star is an important issue both for general relativity and astrophysics, which is related to the well-known “frozen star” paradox. This paradox has been discussed intensively and seems to have been solved in the comoving-like coordinates. However, to a real astrophysical observer within a finite time, this problem should be discussed in the point of view of the distant rest-observer, which is the main purpose of this Letter. Following the seminal work of Oppenheimer and Snyder (1939), we present the exact solution for one or two dust shells collapsing towards a pre-existing black hole. We find that the metric of the inner region of the shell is time-dependent and the clock inside the shell becomes slower as the shell collapses towards the pre-existing black hole. This means the inner region of the shell is influenced by the property of the shell, which is contrary to the result in Newtonian theory. It does not contradict the Birkhoff's theorem, since in our case we cannot arbitrarily select the clock inside the shell in order to ensure the continuity of the metric. This result in principle may be tested experimentally if a beam of light travels across the shell, which will take a longer time than without the shell. It can be considered as the generalized Shapiro effect, because this effect is due to the mass outside, but not inside as the case of the standard Shapiro effect. We also found that in real astrophysical settings matter can indeed cross a black hole's horizon according to the clock of an external observer and will not accumulate around the event horizon of a black hole, i.e., no “frozen star” is formed for an external observer as matter falls towards a black hole. Therefore, we predict that only gravitational wave radiation can be produced in the final stage of the merging process of two coalescing black holes. Our results also indicate that for the clock of an external observer, matter, after crossing the event horizon, will never arrive at the “singularity” (i.e. the exact center of the black hole), i.e., for all black holes with finite lifetimes their masses are distributed within their event horizons, rather than concentrated at their centers. We also present a worked-out example of the Hawking's area theorem. 相似文献
12.
The vacuum Einstein equations in five dimensions are shown to admit a solution describing a stationary asymptotically flat spacetime regular on and outside an event horizon of topology S1xS2. It describes a rotating "black ring." This is the first example of a stationary asymptotically flat vacuum solution with an event horizon of nonspherical topology. The existence of this solution implies that the uniqueness theorems valid in four dimensions do not have simple five-dimensional generalizations. It is suggested that increasing the spin of a spherical black hole beyond a critical value results in a transition to a black ring, which can have an arbitrarily large angular momentum for a given mass. 相似文献
13.
The generalized Stefan--Boltzmann law of a rectilinear non-uniformly accelerating Kinnersley black hole 下载免费PDF全文
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. 相似文献
14.
Hawking effect and quantum nonthermal radiation of an arbitrarily accelerating charged black hole using a new tortoise coordinate transformation 下载免费PDF全文
Using a new tortoise coordinate transformation, this paper investigates the Hawking effect from an arbitrarily accelerating charged black hole by the improved Damour-Ruffini method. After the tortoise coordinate transformation, the Klein-Gordon equation can be written as the standard form at the event horizon. Then extending the outgoing wave from outside to inside of the horizon analytically, the surface gravity and Hawking temperature can be obtained automatically. It is found that the Hawking temperatures of different points on the surface are different. The quantum nonthermal radiation characteristics of a black hole near the event horizon is also discussed by studying the Hamilton-Jacobi equation in curved spacetime and the maximum overlap of the positive and negative energy levels near the event horizon is given. There is a dimensional problem in the standard tortoise coordinate and the present results may be more reasonable. 相似文献
15.
We discuss the propagation of electromagnetic plane waves with negative phase velocity in regular black holes. For this purpose, we consider the Bardeen model as a nonlinear magnetic monopole and the Bardeen model coupled to nonlinear electrodynamics with a cosmological constant. It turns out that the region outside the event horizon of each regular black hole does not support negative phase velocity propagation, while its possibility in the region inside the event horizon is discussed. 相似文献
16.
Jiliang Jing 《Physics letters. [Part B]》2011,705(4):287-291
The asymptotically anti-de Sitter structure near event horizon of general asymptotically flat stationary black hole is found, and the Cardy-Verlinde formula is generalized to the asymptotically flat black holes in the Einstein-Maxwell theory and low-energy effective field theory describing string. The result that the entropy of conformal field theory (CFT) agrees precisely with black-hole entropy provides a CFT interpretation of the Bekenstein-Hawking entropy of the asymptotically flat stationary black holes. 相似文献
17.
Andy T. Augousti Paweł Gusin Bartosz Kuśmierz Jan Masajada Andrzej Radosz 《General Relativity and Gravitation》2018,50(10):131
We present the results of an investigation of the speed of a radially infalling test particle crossing the event horizon of a black hole within a Schwarzschild spacetime. One finds that the speed as measured by a special class of observers, at rest outside the horizon and static inside the horizon, increases when the test particle approaches the horizon but decreases inside the horizon. The corresponding situation regarding black holes possessing both outer and inner horizons is also briefly discussed. 相似文献
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It is a well known analytic result in general relativity that the 2-dimensional area of the apparent horizon of a black hole
remains invariant regardless of the motion of the observer, and in fact is independent of the t = constant slice, which can be quite arbitrary in general relativity. Nonetheless the explicit computation of horizon area is often
substantially more difficult in some frames (complicated by the coordinate form of the metric), than in other frames. Here
we give an explicit demonstration for very restricted metric forms of (Schwarzschild and Kerr) vacuum black holes. In the
Kerr–Schild coordinate expression for these spacetimes they have an explicit Lorentz-invariant form. We consider boosted versions with the black hole moving through the coordinate system. Since these are stationary black hole spacetimes, the
apparent horizons are two dimensional cross sections of their event horizons, so we compute the areas of apparent horizons
in the boosted space with (boosted) t = constant, and obtain the same result as in the unboosted case. Note that while the invariance of area is generic, we deal only with
black holes in the Kerr–Schild form, and consider only one particularly simple change of slicing which amounts to a boost.
Even with these restrictions we find that the results illuminate the physics of the horizon as a null surface and provide
a useful pedagogical tool. As far as we can determine, this is the first explicit calculation of this type demonstrating the
area invariance of horizons. Further, these calculations are directly relevant to transformations that arise in computational
representation of moving black holes. We present an application of this result to initial data for boosted black holes. 相似文献
20.
利用静态球对称黑洞的热质点模型,研究了黑洞的热辐射规律,得到了当η取固有厚度时,对所有Schwarzschild黑洞,其辐射功率都相同,其视界处的辐射能通量与黑洞的质量的平方成反比,而距黑洞遥远的观察者所接收到的辐射能通量与观测者到黑洞的距离的平方成反比; Reissner-Nordstrm黑洞视界处的辐射能通量和辐射功率不仅与黑洞的质量有关,还与黑洞的电荷有关,而距黑洞遥远的观察者所接收到的辐射能通量,当截断的固有厚度η、黑洞的质量m和电荷Q取定后与观测者到黑洞之间的距离的
关键词:
静态球对称黑洞
热质点模型
辐射功率
辐射能通量 相似文献