Quantum Radiation Properties of General Nonstationary Black Hole

Using the generalized tortoise coordinate transformations the quantum radiation properties of Klein-Gordon scalar particles, Maxwell’s electromagnetic field equations, and Dirac equations are investigated in general nonstationary black hole. The locations of the event horizon and the Hawking temperature depend on both time and angles. A new extra coupling effect is observed in the thermal radiation spectrum of Maxwell’s equations and Dirac equations which is absent in the thermal radiation spectrum of scalar particles. We also observe that the chemical potential derived from scalar particles is equal to the highest energy of the negative-energy state of the scalar particle in the nonthermal radiation in general nonstationary black hole. Applying generalized tortoise coordinate transformation a constant termξis produced in the expression of thermal radiation in general nonstationary black hole. It indicates that generalized tortoise coordinate transformation is more accurate and reliable in the study of thermal radiation of black hole.

Quantum radiation of Maxwell’s electromagnetic field in nonstationary Kerr–de Sitter black hole

Quantum radiation properties of nonstationary Kerr–de Sitter (KdS) black hole is investigated using the method of generalized tortoise coordinate transformation. The locations of horizons and the temperature of the thermal radiation as well as the maximum energy of the nonthermal radiation are derived. It is found that the surface gravity and the Hawking temperature depend on both time and different angles. An extra coupling effect is obtained in the thermal radiation spectrum of Maxwell’s electromagnetic field equations which is absent in the thermal radiation spectrum of scalar particles. Further, the chemical potential derived from the thermal radiation spectrum of scalar particle has been found to be equal to the highest energy of the negative energy state of the scalar particle in the nonthermal radiation for KdS black hole. It is also shown that the generalized tortoise coordinate transformation produces a constant term in the expression of the surface gravity and Hawking temperature.

Hawking radiation from a dynamical Kerr–Newman black hole

After Hawking radiation from a Schwarzschild black hole is calculated using the Damour–Ruffini method, the tortoise coordinate transformation in a static black hole is extended to a dynamical axisymmetric black hole, such as a dynamical Kerr–Newman black hole. Under the generalized tortoise coordinate transformation, Hawking radiation from a dynamical Kerr–Newman black hole is obtained successfully. Moreover, it also seems to occur on the apparent horizon instead of the event horizon.

CHARACTERISTICS OF QUANTUM RADIATION OF SLOWLY VARYING NONSTATIONARY KERR–NEWMAN BLACK HOLES

Quantum radiative characteristics of slowly varying nonstationary Kerr–Newman black holes are investigated by using the method of generalized tortoise coordinate transformation. It is shown that the temperature and the shape of the event horizon of this kind of black holes depend on the time and the angle. Further, we reveal a previously ignored relationship between thermal radiation and nonthermal radiation, which is that the chemical potential in the thermal radiation spectrum is equal to the highest energy of the negative energy state of particles in nonthermal radiation for slowly varying nonstationary Kerr–Newman black holes. Also, we show that the deduced general results can be degenerated to the known conclusion of stationary Kerr–Newman black holes.

NON-EXISTENCE OF NEW QUANTUM ERGOSPHERE EFFECT OF A VAIDYA-TYPE BLACK HOLE

Hawking evaporation of Dirac particles and scalar fields in a Vaidya-type black hole is investigated by the method of generalized tortoise coordinate transformation. It is shown that Hawking radiation of Dirac particles does not exist for P1, Q2 components but for P2, Q1 components in any Vaidya-type black holes. Both the location and the temperature of the event horizon change with time. The thermal radiation spectrum of Dirac particles is the same as that of Klein–Gordon particles. We demonstrate that there is no new quantum ergosphere effect in the thermal radiation of Dirac particles in any spherically symmetry black holes.