Higher-dimensional black holes: Braneworld stars and Hawking radiation.

In this thesis two aspects of braneworld models are studied. A new attempt at finding the metric of a braneworld black hole within the second Randall-Sundrum model is explored. Branes containing distributions of perfect fluid are embedded in a variety of 5-dimensional 5O(4)-symmetric bulk spacetimes so that the Israel junction conditions are satisfied. A particular class of time-dependent embeddings are studied and shown to be unable to describe the braneworld black hole. Static trajectories are then investigated in five-dimensional anti-de Sitter and Schwarzschild backgrounds. These reveal a wide variety of permissible trajectories which are classified according to their energy-momentum profiles. The static embedding of branes in a Schwarzschild-anti-de Sitter spacetime is then explored, revealing objects with possible interpretation as "braneworld stars”. The evaporation of higher-dimensional rotating black holes, both on the brane and in the bulk is studied from an analytical perspective. A matching technique is employed to derive the solution for the radial component of the fields of scalars, fermions and gauge bosons propagating in the brane-induced line-element of a higher-dimensional rotating black hole. These solutions are used to calculate Hawking radiation spectra from a black hole in the spin-down phase of its lifetime within the Arkani-Hamed-Dimopoulos-Dvali model. The same method is used to calculate the emission of scalar fields into the bulk spacetime of a higher-dimensional rotating, black hole and a comparison is made between brane and bulk emission rates. Finally the matching technique is applied to the problem of graviton emission in the bulk from a higher-dimensional Schwarzschild black hole.