Modifications to the spectrum of radiation from black holes

Thesis

Despite their name, there is clear theoretical evidence that black holes emit radiation. The nature and spectrum of this radiation depends on many features of the black hole and the emitted particles. With the profound implications that black hole evaporation has on our understanding of the marriage of quantum mechanics and general relativity, it is essential to study the details of this radiation in new contexts.

In this thesis we examine certain important modifications to the spectrum of radiation from black holes that can occur. Firstly, we study the case that the particles emitted by the black hole are spatially extended, rather than pointlike, and find that the rate of emission is suppressed by a factor which depends sensitively on the size of the particle. We then study the emission of electrically charged particles from black holes from a perspective that elucidates the physical picture of emission; namely, in terms of tunnelling of particles both through the horizon and the external electric field. We finally consider the cosmological consequences of modifying the mass-temperature relation of black holes by supposing that they can radiate into higher dimensions. In particular, we argue that current constraints on the density of black holes in the universe are evaded in certain extra-dimensional theories, in which black holes are substantially colder than their four-dimensional counterparts.

Authors: Johnson, G

• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English