BOUNDING THE GREYBODY FACTORS FOR NON-ROTATING BLACK HOLES

Abstract

Semiclassical black holes emit radiation called Hawking radiation. Such radiation, as seen by an asymptotic observer far outside the black hole, differs from the original radiation near the horizon of the black hole by a redshift factor and the so-called "greybody factor." In this paper, we concentrate on the greybody factor; various bounds for the greybody factors of non-rotaging black holes are obtained, concentrating primarily on charged Reissner–Nordström (RN) and RN–de Sitter black holes. These bounds can be derived using a 2 × 2 transfer matrix formalism. It is found that the charges of black holes act as efficient barriers. Furthermore, adding extra dimensions to spacetime can shield Hawking radiation. Finally, it is also found that the cosmological constant can increase the emission rate of Hawking radiation.