Classical black holes are defined by the property that things can go in, but don’t come out. However, Stephen Hawking calculated that black holes actually radiate quantum mechanical particles. The two important ingredients that result in back hole evaporation are (1) the spacetime geometry, in particular the black hole horizon, and (2) the fact that the notion of a “particle” is not an invarian...

It has been proposed that a black hole horizon should generate Hawking radiation. In order to test this theory, we have created a narrow, low density, very low temperature atomic Bose-Einstein condensate, containing an analog black hole horizon and an inner horizon, as in a charged black hole. We observe Hawking radiation emitted by the black hole. This is the output of the black hole laser. We...

We show that the Abelian Higgs field equations in the background of the four dimensional AdS-Schwarzschild black hole have a vortex line solution. This solution, which has axial symmetry, is a generalization of the AdS spacetime Nielsen-Olesen string. By a numerical study of the field equations, we show that black hole could support the Abelian Higgs field as its Abelian hair. Also, we conside ...

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 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....