Hawking radiation from a dynamical Kerr–Newman black hole

Abstract

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.