N = 2 supersymmetric quantum black holes in the heterotic S-T -U model are presented. In particular three classes of axion-free quantum black holes with half the N = 2, D = 4 supersymmetries unbroken are considered. First, these quantum black holes are investigated at generic points in moduli space. Then “linearized” non-abelian black holes are considered, which can occur at critical points of ...

We consider boson stars and black holes in scalar electrodynamics with a V-shaped scalar potential. The boson stars come in two types, having either ball-like or shell-like charge density. We analyze the properties of these solutions and determine their domains of existence. When mass and charge become equal, the space-times develop a throat. The shell-like solutions need not be globally regula...

Motivated by the recent interest in quantization of black hole area spectrum, we consider the area spectrum of Schwarzschild, BTZ, extremal Reissner-Nordström, near extremal Schwarzschild-de Sitter, and Kerr black holes. Based on the proposal by Bekenstein and others that the black hole area spectrum is discrete and equally spaced, we implement Kunstatter's method to derive the area spectrum fo...

In this paper we analyze certain aspects of virtual black holes. We see how quantum bubble is the representative of creation and annihilation of a pair of virtual black holes that satisfy the Wheeler-DeWitt equation. We calculate the loss of quantum coherence due to these virtual black holes and also see how these virtual black holes give space-time an intrinsic entropy.

We study a generalisation of thermodynamic geometry to degenerate quantum ground states at zero temperatures exemplified by charged extremal black holes in type II string theories. Several examples of extremal charged black holes with non degenerate thermodynamic geometries and finite but non zero state space scalar curvatures are established. These include black holes described by D1-D5-P and ...

We review black-hole solutions of higher-dimensional vacuum gravity and higher-dimensional supergravity theories. The discussion of vacuum gravity is pedagogical, with detailed reviews of Myers-Perry solutions, black rings, and solution-generating techniques. We discuss black-hole solutions of maximal supergravity theories, including black holes in anti-de Sitter space. General results and open...

I show that de Sitter space disintegrates into an infinite number of copies of itself. This occurs iteratively through a quantum process involving two types of topology change. First a handle is created semiclassically, on which multiple black hole horizons form. Then the black holes evaporate and disappear, splitting the spatial hypersurfaces into large parts. Applied to cosmology, this proces...

We determine coherent states peaked at classical space-time of the Schwarzschild black hole in the frame-work of canonical quantisation of general relativity. The information about the horizon is naturally encoded in the phase space variables, and the perturbative quantum fluctuations around the classical geometry depend on the distance from the horizon. For small black holes, space near the vi...

After a brief review of Gödel-type universes in string theory, we discuss some intriguing properties of black holes immersed in such backgrounds. Among these are the upper bound on the entropy that points towards a finite-dimensional Hilbert space of a holographically dual theory, and the minimum black hole temperature that is reminiscent of the Hawking-Page transition. Furthermore, we discuss ...