# Quantum Radiation Properties of General Nonstationary Black Hole

## TL;DR

This paper investigates quantum radiation from non-stationary black holes, revealing dependencies on time and angles, and identifies a new coupling effect in electromagnetic and Dirac fields absent in scalar radiation.

## Contribution

It introduces a generalized tortoise coordinate transformation method that accurately captures the thermal radiation properties of various quantum fields in dynamic black hole spacetimes.

## Key findings

- Event horizon and Hawking temperature depend on time and angles.
- A new coupling effect appears in electromagnetic and Dirac radiation spectra.
- The generalized tortoise coordinate transformation yields a more precise thermal radiation expression.

## Abstract

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 non-stationary 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 non-thermal radiation in general non-stationary black hole. Applying generalized tortoise coordinate transformation a constant term $\xi$ is produced in the expression of thermal radiation in general non-stationary black hole. It indicates that generalized tortoise coordinate transformation is more accurate and reliable in the study of thermal radiation of black hole.