On black holes in string theory

Abstract

This thesis investigates black holes in string theory through string amplitudes and through gauge-gravity duality. The research presented in this thesis supports the claim that string theory is capable of a consistent quantum-mechanical description of black holes and develops techniques which may prove useful in testing this claim in new scenarios. The thesis comprises two parts. Part I describes novel disk amplitudes which derive the supergravity elds sourced by a D-brane with a travelling wave, and Part II describes free particle structures arising in a matrix model which is related through gauge-gravity duality to asymptotically anti-de Sitter black holes. The disk amplitudes calculated in Part I provide a direct connection between the microscopic worldsheet description of a D-brane with a travelling wave and its macroscopic supergravity description. A D-brane carrying a travelling wave can be mapped via string dualities to the two-charge D1-D5 black hole and this research opens up the possibility to use these techniques to study the three-charge D1-D5-P black hole. Part II of the thesis identi es free particle descriptions of non-holomorphic operators in a complex matrix model derived from dimensional reduction of N = 4 Super-Yang-Mills theory. This research generalizes the free particle description in the half-BPS sector of this theory which was realized in supergravity and enabled studies of the microscopics of singular geometries. The free particle descriptions have been derived at zero gauge coupling; if these or similar structures are also present at strong coupling this research could be used to study the microscopics of non-extremal asymptotically anti-de Sitter black holes.