Origin of Hawking radiation: firewall or atmosphere?

The Unruh vacuum not admitting any outgoing flux at the horizon implies that the origin of the outgoing Hawking radiation is the atmosphere of a near-horizon quantum region without resort to the firewall; however, the existence of the firewall of superplanckian excitations at the horizon can be supported by the infinite Tolman temperature at the horizon. In an exactly soluble model, we explicitly show that the firewall necessarily emerges out of the Unruh vacuum so that the Tolman temperature in the Unruh vacuum is divergent in essence due to the infinitely blueshifted negative ingoing flux crossing the horizon rather than the outgoing flux. We also show that the outgoing Hawking radiation in the Unruh vacuum indeed originates from the atmosphere, not just at the horizon, which is of no relevance to the infinite blueshift. Consequently, the firewall from the infinite Tolman temperature and the Hawking radiation from the atmosphere turn out to be compatible, once we waive the claim that the Hawking radiation in the Unruh vacuum originates from the infinitely blueshifted outgoing excitations at the horizon.     

General Tortoise Coordinate Transformation in a Dynamical Kerr-Newman Black Hole

Under the extended dynamical tortoise coordinate transformation, Damour-Ruffini method has been applied to calculate the charged particles’ Hawking radiation from the apparent horizon of a dynamical Kerr-Newman black hole. It is shown that Hawking radiation is still purely thermal black body spectrum. Moreover, the temperature of Hawking radiation is corresponding to the apparent horizon surface gravity and the first law of thermodynamics can also be constructed successfully on the apparent horizon in the dynamical Kerr-Newman black hole.     

Fermions tunneling from apparent horizon of FRW universe

In the paper [R.-G. Cai, L.-M. Cao, Y.-P. Hu, arXiv: 0809.1554], the scalar particles' Hawking radiation from the apparent horizon of Friedmann–Robertson–Walker (FRW) universe was investigated by using the tunneling formalism. They obtained the Hawking temperature associated with the apparent horizon, which was extensively applied in investigating the relationship between the first law of thermodynamics and Friedmann equations. In this Letter, we calculate fermions' Hawking radiation from the apparent horizon of FRW universe via tunneling formalism. Applying WKB approximation to the general covariant Dirac equation in FRW spacetime background, the radiation spectrum and Hawking temperature of apparent horizon are correctly recovered, which supports the arguments presented in the paper [R.-G. Cai, L.-M. Cao, Y.-P. Hu, arXiv: 0809.1554].     

Quantum thermal effects of a radiating rotating charged black hole

Asymptotic solutions of the Klein-Gordon equation in a region near the event horizon of a radiating rotating charged black hole are obtained by using generalized tortoise coordinates. The location of the event horizon and the Hawking temperature of the black hole are given. Both the horizon and the temperature depend on the angle and time, due to radiation. However, they are independent of the angle if either rotation or radiation vanishes. The treatment encompasses as special cases the results on a number of well-known black holes.     

HAWKING EFFECT OF DIRAC PARTICLES IN VAIDYA-SCHWARZSCHILD-DE SITTER SPACE-TIME

The solutions of the Dirac equation near the black hole event horizon and the universe horizon in the Vaidya-Schwarzschild-de Sitter space-time are given in this paper. Both the temperature of the Hawking radiation and the location of the evaporating black hole horizon and the universe horizon are determined exactly.     

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.     

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     

Quantum nonthermal radiation and horizon surface gravity of an arbitrarily accelerating black hole with electric charge and magnetic charge

With a new tortoise coordinate transformation, we discussed the quantum nonthermal radiation characteristics near the event horizon by studying the Hamilton-Jacobi equation of a scalar particle in the curve space-time, and obtained the event horizon surface gravity and the Hawking temperature on the event horizon. The results showed that there is a crossing of particle energy near the event horizon. We derived the maximum overlap of the positive and negative energy levels. It was also found that the Hawking temperature of a black hole depends on not only the time, but also the angle. There is a problem of dimension in the usual tortoise coordinate, so the present results obtained by using a correct-dimension new tortoise coordinate transformation may be more reasonable.     

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.     

Radiation Energy Flux and Radiation Power of Schwarzschild Black Hole

Applying the entropy density near the event horizon, we obtained the result that the radiation energy flux of the black hole is always proportional to the quartic of the temperature of its event horizon. That is to say, the thermal radiation of the black hole always satisfies the generalized Stefan–Boltzmann law. The derived generalized Stefan–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 which is related to the black hole mass, the kinds of radiation particles and space–time metric near the event horizon. In this paper, we have put forward a thermal particle model in curved space–time. By this model, the result has been obtained that when the thin film thickness and the cut-off distance are both fixed, the radiation energy flux received by observer far away from the Schwarzschild black hole is proportional to the average radial effusion velocity of the radiation particles in the thin film, and inversely proportional to the square of the distance between the observer and the black hole.     

LETTER: The Nernst Theorem and the Entropy of the Reissner–Nordström Black Hole

We calculate the free energy and the entropy of a scalar field in terms of the brick-wall method on the background of the Reissner–Nordström black hole. We obtain the entropy of a scalar field is not only related to the location of an outer horizon but also is the function of the location of an inner horizon. In the approximation, the entropy is only proportional to the area of an outer horizon. The entropy expressed by location parameter of outer and inner horizon approaches zero, when the radiation temperature of a black hole approaches absolute zero. It satisfies the Nernst theorem.     

Conformally rescaled spacetimes and Hawking radiation

We study various derivations of Hawking radiation in conformally rescaled metrics. We focus on two important properties, the location of the horizon under a conformal transformation and its associated temperature. We find that the production of Hawking radiation cannot be associated in all cases to a trapping horizon because its location is not invariant under a conformal transformation. We also find evidence that the temperature of the Hawking radiation should transform simply under a conformal transformation, being invariant for asymptotic observers in the limit that the conformal transformation factor is unity at their location.     

A quantal Tolman temperature

The conventional Tolman temperature based on the assumption of the traceless condition of energy-momentum tensor for matter fields is infinite at the horizon if Hawking radiation is involved. However, we note that the temperature associated with Hawking radiation is of relevance to the trace anomaly, which means that the traceless condition should be released. So, a trace anomaly-induced Stefan-Boltzmann law is newly derived by employing the first law of thermodynamics and the property of the temperature independence of the trace anomaly. Then, the Tolman temperature is quantum-mechanically generalized according to the anomaly-induced Stefan-Boltzmann law. In an exactly soluble model, we show that the Tolman factor does not appear in the generalized Tolman temperature which is eventually finite everywhere, in particular, vanishing at the horizon. It turns out that the equivalence principle survives at the horizon with the help of the quantum principle, and some puzzles related to the Tolman temperature are also resolved.     

Hawking radiation from a Vaidya black hole by Hamilton-Jacobi method

Using the Hamilton-Jacobi method, Hawking radiation from the apparent horizon of a dynamical Vaidya black hole is calculated. The black hole thermodynamics can be built successfully on the apparent horizon. If a relativistic perturbation is given to the apparent horizon, a similar calculation can also lead to a purely thermal spectrum, which corresponds to a modified temperature from the former. The first law of thermodynamics can also be constructed successfully at a new supersurface which has a small deviation from the apparent horizon. When the event horizon is thought as such a deviation from the apparent horizon, the expressions of the characteristic position and temperature are consistent with the previous result that asserts that thermodynamics should be built on the event horizon. It is concluded that the thermodynamics should be constructed on the apparent horizon exactly while the event horizon thermodynamics is just one of the perturbations near the apparent horizon.     

The origin of thermal hadron production

Multihadron production in high energy collisions, from e⁺e^- annihilation to heavy ion interactions, shows remarkable thermal behaviour, specified by a universal “Hagedorn” temperature. We argue that this hadronic radiation is formed by tunneling through the event horizon of colour confinement, i.e., that it is the QCD counterpart of Hawking-Unruh radiation from black holes. It is shown to be emitted at a universal temperature T_H ≃ (σ/2 π)^1/2, where σ denotes the string tension. Since the event horizon does not allow information transfer, the radiation is thermal “at birth”.     

Hawking Radiation of Dirac Particles on Rindler Horizon to a Uniformly Accelerating Observer

Following the method of Damour and Ruffini, the Hawking radiation of Dirac particles on Rindler horison to a uniformly accelerating observer is studied this paper. The temperature on Rindler horizon surface and the thermal spectrum formula of Dirac particles are obtained. The result is discussed.     

Fluctuation around horizon on a Schwarzschild black hole using the null geodesic method

Using the null geodesic method, Hawking radiation from the horizon of a Schwarzschild black hole is calculated. The thermodynamics can be built successfully on the horizon where the apparent horizon and event horizon are coincident with each other. When a relativistic perturbation is given to the horizon, the first law of thermodynamics can also be constructed at a new supersurface near the horizon successfully. The expressions of the characteristic position and temperature are consistent with the previous result while the thermodynamics was built on the event horizon in a Vaidya black hole. Therefore, the thermodynamics of a dynamical black hole should be constructed on the apparent horizon exactly, and the event horizon thermodynamics is just one of the perturbations near the apparent horizon.     

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)     

Hawking radiation of Weyl neutrinos in a rectilinearly non—uniformly accelerating Kinnersley black hole

The quantum thermal effect of Weyl neutrinos in a rectilinearly non-uniformly accelerating Kinnersley black hole is investigated using the generalized tortoise coordinate transformation.The equations that determine the location,the Hawking temperature of the event horizon and the thermal radiation spectrum of neutrinos are derived.Our results show that the location and the temperature of the event horizon depend not only on the time but also on the angle.     

Quantum Thermal Effect of Nonstationary Kerr-Newman Black Hole

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.