Hawking Radiation as Tunneling

We present a short and direct derivation of Hawking radiation as a tunneling process, based on particles in a dynamical geometry. The imaginary part of the action for the classically forbidden process is related to the Boltzmann factor for emission at the Hawking temperature. Because the derivation respects conservation laws, the exact spectrum is not precisely thermal. We compare and contrast the problem of spontaneous emission of charged particles from a charged conductor.Comment: LaTeX, 10 pages; v2. journal version, added section on relation of black hole radiation to electric charge emission from a charged conducting sphere; v3. restored cut referenc

Doppler tomography of relativistic accretion disks

Spectral lines from a source orbiting around a compact object are studied. Time variations of observed frequency and count rate due to motion of the source and gravitational lensing are considered. Gravitational field of the central object is described by the Kerr metric. It is shown that: (i) simultaneous temporal and frequency resolution enables us to restrict parameters of the model (inclination angle, position of the source, angular momentum of the black hole); (ii) techniques of image restoration, familiar from other fields of astronomy, can be applied to study inner regions of active galactic nuclei. This contribution is relevant for extremely variable X-ray sources with high parameter of efficiency, such as Seyfert 1 galaxy PHL 1092 observed by ROSAT.Comment: 12 pages, to appear in Publications of the Astronomical Society of Japan, Vol. 48 (October 1996), figures available upon request from the authors, or at http://otokar.troja.mff.cuni.cz/user/karas/au_www/karas/papers.ht

Connection between two forms of extra-dimensional metrics revisited

5D cosmological model with 3-brane with matter is considered. The brane divides bulk in two AdS half spaces. Geometry of the model can be described by two types of coordinates: in the first setting the metric is static and the brane is moving in the bulk, in the second approach the metric is time-dependent and the brane is located at a fixed position in the bulk. Coordinate transformation connecting two coordinate systems is constructed.Comment: 7 page

On Nonperturbative Exactness of Konishi Anomaly and the Dijkgraaf-Vafa Conjecture

In this paper we study the nonperturbative corrections to the generalized Konishi anomaly that come from the strong coupling dynamics of the gauge theory. We consider U(N) gauge theory with adjoint and Sp(N) or SO(N) gauge theory with symmetric or antisymmetric tensor. We study the algebra of chiral rotations of the matter field and show that it does not receive nonperturbative corrections. The algebra implies Wess-Zumino consistency conditions for the generalized Konishi anomaly which are used to show that the anomaly does not receive nonperturbative corrections for superpotentials of degree less than 2l+1 where 2l=3c(Adj)-c(R) is the one-loop beta function coefficient. The superpotentials of higher degree can be nonperturbatively renormalized because of the ambiguities in the UV completion of the gauge theory. We discuss the implications for the Dijkgraaf-Vafa conjecture.Comment: 23 page

BTZ Black Hole with Chern-Simons and Higher Derivative Terms

The entropy of a BTZ black hole in the presence of gravitational Chern-Simons terms has previously been analyzed using Euclidean action formalism. In this paper we treat the BTZ solution as a two dimensional black hole by regarding the angular coordinate as a compact direction, and use Wald's Noether charge method to calculate the entropy of this black hole in the presence of higher derivative and gravitational Chern-Simons terms. The parameters labelling the black hole solution can be determined by extremizing an entropy function whose value at the extremum gives the entropy of the black hole.Comment: LaTeX file, 11 page