A wave impinging on a Kerr black hole can be amplified as it scatters off the hole if certain conditions are satisfied giving rise to superradiant scattering. By placing a mirror around the black hole one can make the system unstable. This is the black hole bomb of Press and Teukolsky. We investigate in detail this process and compute the growing timescales and oscillation frequencies as a func...

We review recent developments concerning supersymmetric black holes in string theory. After a general introduction to the laws of black hole mechanics and to black hole entropy in string theory, we discuss black hole solutions in N = 2 supergravity, special geometry, the black hole attractor equations and the underlying variational principle. Special attention is payed to the crucial role of hi...

We discuss the quantum mechanics and thermodynamics of the (2+1)dimensional black hole, using both minisuperspace methods and exact results from Chern-Simons theory. In particular, we evaluate the first quantum correction to the black hole entropy. We show that the dynamical variables of the black hole arise from the possibility of a deficit angle at the (Euclidean) horizon, and briefly specula...

This paper presents a continuation of our efforts to numerically study accretion disks that are misaligned (tilted) with respect to the rotation axis of a Kerr black hole. Here we present results of a global numerical simulation which fully incorporates the effects of the black hole spacetime as well as magnetorotational turbulence that is the primary source of angular momentum transport in the...

A 5D black hole(M 5) is investigated in the type IIB superstring theory com-pactified on S 1 ×T 4. This corresponds to AdS 3 ×S 3 ×T 4 in the near horizon with asymptotically flat space. Here the harmonic gauge is introduced to decouple the mixing between the dilaton and others. On the other hand we obtain the BTZ balck hole(AdS 3 ×S 3 ×T 4) as the non-dilatonic solution. We calculate the greyb...

I start with a discussion of the no-hair principle. The hairy black hole solutions of recent vintage do not deprive it of value because they are often unstable. Generic properties of spherical static black holes with nonvacuum exteriors are derived. These form the basis for the discussion of the new no scalar hair theorems. I discuss the generic phenomenon of superradiance for its own sake, as ...

Black hole–neutron star (BHNS) binaries are important sources of gravitational waves for second-generation interferometers, and BHNS mergers are also a proposed engine for short, hard gamma-ray bursts. The behavior of both the spacetime (and thus the emitted gravitational waves) and the neutron star matter in a BHNS merger depend strongly and nonlinearly on the black hole’s spin. While there is...

The rapid TeV γ−ray variability detected in the well-known nearby radio galaxy M87 implies an extremely compact emission region (5 − 10 Schwarzschild radii) near the horizon of the supermassive black hole in the galactic center. TeV photons are affected by dilution due to interaction with the radiation field of the advectiondominated accretion flow (ADAF) around the black hole, and can thus be ...