After recalling the definition of black holes, and reviewing their energetics and their classical thermodynamics, one expounds the conjecture of Bekenstein, attributing an entropy to black holes, and the calculation by Hawking of the semi-classical radiation spectrum of a black hole, involving a thermal (Planckian) factor. One then discusses the attempts to interpret the black-hole entropy as t...

Black holes are by definition black, and therefore cannot be directly observed by using electromagnetic radiations. Convincing identification of black holes must necessarily depend on the identification of a very specially behaving matter and radiation which surround them. A major problem in this subject of black hole astrophysics is to quantify the behaviour of matter and radiation close to th...

We show that a class of four-dimensional rotating black holes allow fivedimensional embeddings as black rotating strings. Their near-horizon geometry factorizes locally as a product of the three-dimensional anti-deSitter spacetime and a two-dimensional sphere (AdS3 × S2), with angular momentum encoded in the global space-time structure. Following the observation that the isometries on the AdS3 ...

Unlike the extremal Reissner-Nordström black hole in ordinary spacetime, the one in anti-de Sitter spacetime is a minimum of action and has zero entropy if quantization is carried out after extremaliza-tion. However, if extremalization is carried out after quantization, then the entropy is a quarter of the area as in the usual case. While the entropy of ordinary (non-extremal) black holes has b...

We construct exact static, axisymmetric solutions of Einstein-Maxwell-dilaton gravity presenting distorted charged dilaton black holes. The thermodynamics of such distorted black holes is also discussed.

Galactic stellar-population-synthesis models, chemical-enrichment models, and longduration Bulge microlensing events indicate about Ntot = 10 − 10 stellar-mass black holes reside in our Galaxy. We study X-ray emission from accretion from the interstellar medium on to isolated black holes. Although isolated black holes may be fewer in number than neutron stars, NNS ∼ 10, their higher masses, 〈M〉...

These lectures review some of the recent progress in uncovering the phase structure of black hole solutions in higher-dimensional vacuum Einstein gravity. The two classes on which we focus are Kaluza-Klein black holes, i.e. static solutions with an event horizon in asymptotically flat spaces with compact directions, and stationary solutions with an event horizon in asymptotically flat space. Hi...

We propose a strategy for searching for isolated stellar mass black holes in the solar neighborhood with the Sloan Digital Sky Survey. Due to spherical accretion of the inter-stellar medium and the ambient magnetic field, an isolated black hole is expected to emit a blended, thermal synchrotron spectrum with a roughly flat peak from the optical down to the far infra-red. We find that the Sloan ...

Unlike the extremal Reissner-Nordström black hole in ordinary spacetime, the one in anti-de Sitter spacetime is a minimum of action and has zero entropy if quantization is carried out after extremaliza-tion. However, if extremalization is carried out after quantization, then the entropy is a quarter of the area as in the usual case. While the entropy of ordinary (non-extremal) black holes has b...

The greybody factors for spin 1 2 particles in the BTZ black holes are discussed from 2D CFT in bulk-boundary correspondence. It is found that the initial state of spin 1 2 particle in the BTZ black holes can be described by the Poincaré vacuum state in boundary 2D CFT, and the nonlinear coordinate transformation causes the thermalization of the Poincaré vacuum state. For special case, our resu...