123 research outputs found
"No-Scalar-Hair" Theorems for Nonminimally Coupled Fields with Quartic Self-Interaction
Self-gravitating scalar fields with nonminimal coupling to gravity and having
a quartic self-interaction are considered in the domain of outer communications
of a static black hole. It is shown that there is no value of the nonminimal
coupling parameter for which nontrivial static black hole solutions
exist. This result establishes the correctness of Bekenstein ``no-scalar-hair''
conjecture for quartic self-interactions.Comment: 8 pages, RevTeX
Regular Magnetic Black Holes and Monopoles from Nonlinear Electrodynamics
It is shown that general relativity coupled to nonlinear electrodynamics
(NED) with the Lagrangian , having a correct weak field
limit, leads to nontrivial static, spherically symmetric solutions with a
globally regular metric if and only if the electric charge is zero and
tends to a finite limit as . Properties and examples of such
solutions, which include magnetic black holes and soliton-like objects
(monopoles), are discussed. Magnetic solutions are compared with their electric
counterparts. A duality between solutions of different theories specified in
two alternative formulations of NED (called duality) is used as a tool for
this comparison.Comment: 6 pages, Latex2e. One more theorem, some comments and two references
have been added. Final journal versio
No-Hair Theorem for Spontaneously Broken Abelian Models in Static Black Holes
The vanishing of the electromagnetic field, for purely electric
configurations of spontaneously broken Abelian models, is established in the
domain of outer communications of a static asymptotically flat black hole. The
proof is gauge invariant, and is accomplished without any dependence on the
model. In the particular case of the Abelian Higgs model, it is shown that the
only solutions admitted for the scalar field become the vacuum expectation
values of the self-interaction.Comment: 8 pages, 2 figures, RevTeX; some changes to match published versio
Black hole solutions in Euler-Heisenberg theory
We construct static and spherically symmetric black hole solutions in the
Einstein-Euler-Heisenberg (EEH) system which is considered as an effective
action of a superstring theory. We considered electrically charged,
magnetically charged and dyon solutions. We can solve analytically for the
magnetically charged case. We find that they have some remarkable properties
about causality and black hole thermodynamics depending on the coupling
constant of the EH theory and , though they have central singularity as
in the Schwarzschild black hole.Comment: 8 pages, 13 figures, figures corrected and some comments adde
Non-Abelian Einstein-Born-Infeld Black Holes
We construct regular and black hole solutions in SU(2) Einstein-Born-Infeld
theory. These solutions have many features in common with the corresponding
SU(2) Einstein-Yang-Mills solutions. In particular, sequences of neutral
non-abelian solutions tend to magnetically charged limiting solutions, related
to embedded abelian solutions. Thermodynamic properties of the black hole
solutions are addressed.Comment: LaTeX, 14 pages, 6 postscript figures; typos corrected in reference
Regular Black Hole in General Relativity Coupled to Nonlinear Electrodynamics
The first regular exact black hole solution in General Relativity is
presented. The source is a nonlinear electrodynamic field satisfying the weak
energy condition, which in the limit of weak field becomes the Maxwell field.
The solution corresponds to a charged black hole with |q| \leq 2 s_c m \approx
0.6 m, having the metric, the curvature invariants, and the electric field
regular everywhere.Comment: 5 pages, RevTex, 6 figure
Vacuum polarization of massive scalar fields in the spacetime of the electrically charged nonlinear black hole
The approximate renormalized stress-energy tensor of the quantized massive
conformally coupled scalar field in the spacetime of electrically charged
nonlinear black hole is constructed. It is achieved by functional
differentiation of the lowest order of the DeWitt-Schwinger effective action
involving coincidence limit of the Hadamard-Minakshisundaram-DeWitt-Seely
coefficient The result is compared with the analogous result derived
for the Reissner-Nordstr\"om black hole. It is shown that the most important
differences occur in the vicinity of the event horizon of the black hole near
the extremality limit. The structure of the nonlinear black hole is briefly
studied by means of the Lambert functions.Comment: 22 pages, 10 figure
The family of regular interiors for non-rotating black holes with
We find the general solution for the spacetimes describing the interior of
static black holes with an equation of state of the type (
being the stress-energy tensor). This form is the one expected from taking into
account different quantum effects associated with strong gravitational fields.
We recover all the particular examples found in the literature. We remark that
all the solutions found follow the natural scheme of an interior core linked
smoothly with the exterior solution by a transient region. We also discuss
their local energy properties and give the main ideas involved in a possible
generalization of the scheme, in order to include other realistic types of
sources.Comment: 31 pages, 1 figure, version to appear in Physical Review
Dyonic BIon black hole in string inspired model
We construct static and spherically symmetric particle-like and black hole
solutions with magnetic and/or electric charge in the
Einstein-Born-Infeld-dilaton-axion system, which is a generalization of the
Einstein-Maxwell-dilaton-axion (EMDA) system and of the Einstein-Born-Infeld
(EBI) system. They have remarkable properties which are not seen for the
corresponding solutions in the EMDA and the EBI system.Comment: 13 pages, 15 figures, Final version in PR
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