Recently, we derived an improved universal upper bound to the entropy of a charged system S ≤ π(2Eb − q2)/h̄. There was, however, some uncertainty in the value of the numerical factor which multiply the q2 term. In this paper we remove this uncertainty; we rederive this upper bound from an application of the generalized second law of thermodynamics to a gedanken experiment in which an entropy-be...

The quantum string emission by Black Holes is computed in the framework of the ‘string analogue model’ (or thermodynamical approach), which is well suited to combine quantum field theory (QFT) and string theory in curved backgrounds (particulary here, as black holes and strings posses intrinsic thermal features and temperatures). String theory properly describes black-hole evaporation. The blac...

We investigate two-dimensional dilaton gravity models with a power-law dilaton potential, whose black hole solutions contain, among others, the dimensional reduction of the Schwarzschild black hole, the Anti-de Sitter black hole and Rindler spacetime. We show that the ground state of these models satisfies simple transformation laws under the SL(2, R) conformal group. We use these transformatio...

We consider a general, classical theory of gravity in n dimensions, arising from a diffeomorphism invariant Lagrangian. In any such theory, to each vector field, ξ, on spacetime one can associate a local symmetry and, hence, a Noether current (n− 1)-form, j, and (for solutions to the field equations) a Noether charge (n− 2)form, Q, both of which are locally constructed from ξ and the the fields...

We calculate perturbative quantum gravity corrections to generic eternal two-dimensional dilaton gravity spacetimes. We estimate the leading corrections to the AdS2 black hole entropy and determine the quantum modification of N -dimensional Schwarzschild spacetime. ∗ [email protected] † [email protected] In recent years, two-dimensional dilaton gravity has earned a great deal of attentio...

We study the evolution of an evaporating rotating black hole, described by the Kerr metric, which is emitting either solely massless scalar particles or a mixture of massless scalar and nonzero spin particles. Allowing the hole to radiate scalar particles increases the mass loss rate and decreases the angular momentum loss rate relative to a black hole which is radiating nonzero spin particles....

We study the evolution of an evaporating rotating black hole, described by the Kerr metric, which is emitting either solely massless scalar particles or a mixture of massless scalar and nonzero spin particles. Allowing the hole to radiate scalar particles increases the mass loss rate and decreases the angular momentum loss rate relative to a black hole which is radiating nonzero spin particles....

Some aspects of the rotating three-dimensional Einstein-Anti-de-Sitter black hole solution, constructed recently by Banados, Teitelboim and Zanelli are discussed. It is shown explicitly that this black hole represents the most general black hole type solution of the Einstein-Anti-de-Sitter theory. The interpretation of one of the integrals of motion as the spin is discussed. Its physics relies ...

With a help of hydrodynamical models, we explore fundamental modes of gas flow in central parts of a galaxy potential with non-axisymmetric perturbations of various strengths. Our grid-based algorithm allows us to get a detailed picture of gas dynamics down to about 10 pc from the galaxy center, where the central black hole becomes dominant. Gas inflow in a bar with an Inner Lindblad Resonance ...