5,063 research outputs found
Perturbations in the Kerr-Newman Dilatonic Black Hole Background: I. Maxwell waves
In this paper we analyze the perturbations of the Kerr-Newman dilatonic black
hole background. For this purpose we perform a double expansion in both the
background electric charge and the wave parameters of the relevant quantities
in the Newman-Penrose formalism. We then display the gravitational, dilatonic
and electromagnetic equations, which reproduce the static solution (at zero
order in the wave parameter) and the corresponding wave equations in the Kerr
background (at first order in the wave parameter and zero order in the electric
charge). At higher orders in the electric charge one encounters corrections to
the propagations of waves induced by the presence of a non-vanishing dilaton.
An explicit computation is carried out for the electromagnetic waves up to the
asymptotic form of the Maxwell field perturbations produced by the interaction
with dilatonic waves. A simple physical model is proposed which could make
these perturbations relevant to the detection of radiation coming from the
region of space near a black hole.Comment: RevTeX, 36 pages in preprint style, 1 figure posted as a separate PS
file, submitted to Phys. Rev.
New perturbative solutions of the Kerr-Newman dilatonic black hole field equations
This work describes new perturbative solutions to the classical,
four-dimensional Kerr--Newman dilaton black hole field equations. Our solutions
do not require the black hole to be slowly rotating. The unperturbed solution
is taken to be the ordinary Kerr solution, and the perturbation parameter is
effectively the square of the charge-to-mass ratio of the
Kerr--Newman black hole. We have uncovered a new, exact conjugation (mirror)
symmetry for the theory, which maps the small coupling sector to the strong
coupling sector (). We also calculate the gyromagnetic ratio of
the black hole.Comment: Revtex, 27 page
Adjoint operators, gauge invariant perturbations, and covariant symplectic structure for black holes in string theory
Expressions for the general and complete perturbations in terms of Debye
potentials of static charged black holes in string theory, valid for curvature
below the Planck scale, are derived starting from a decoupled set of equations
and using Wald's method of adjoint operators. Our results cover both extremal
and nonextremal black holes and are valid for arbitrary values of the dilaton
coupling parameter. The decoupled set is obtained using the Newman-Penrose
formulation of the Einstein-Maxwell-dilaton theory and involves naturally field
quantities invariant under both ordinary gauge transformations of the
electromagnetic potential perturbations and infinitesimal rotations of the
perturbed tetrad. Furthermore, using the recent pointed out relationship
between adjoint operators and conserved currents, a local continuity law for
the field perturbations in terms of the potentials is also obtained. It is
shown that such continuity equation implies the existence of conserved
quantities and of a covariant symplectic structure on the phase space. Future
extensions of the present results are discussed.Comment: LaTeX, 36 pages, submitted to J. Math. Phys. (2002
Complete Semiclassical Treatment of the Quantum Black Hole Problem
Two types of semiclassical calculations have been used to study quantum
effects in black hole backgrounds, the WKB and the mean field approaches. In
this work we systematically reconstruct the logical implications of both
methods on quantum black hole physics and provide the link between these two
approaches. Our conclusions completely support our previous findings based
solely on the WKB method: quantum black holes are effectively p-brane
excitations and, consequently, no information loss paradox exists in this
problem.Comment: 14 pages, REVTE
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