145 research outputs found
Brane-world stars from minimal geometric deformation, and black holes
We build analytical models of spherically symmetric stars in the brane-world,
in which the external space-time contains both an ADM mass and a tidal charge.
In order to determine the interior geometry, we apply the principle of minimal
geometric deformation, which allows one to map General Relativistic solutions
to solutions of the effective four-dimensional brane-world equations. We
further restrict our analysis to stars with a radius linearly related to the
total General Relativistic mass, and obtain a general relation between the
latter, the brane-world ADM mass and the tidal charge. In these models, the
value of the star's radius can then be taken to zero smoothly, thus obtaining
brane-world black hole metrics with a tidal charge solely determined by the
mass of the source and the brane tension. General conclusions regarding the
minimum mass for semiclassical black holes will also be drawn.Comment: 23 pages, 2 figures, references added and update
The Minimal Geometric Deformation Approach Extended
The minimal geometric deformation approach was introduced in order to study
the exterior space-time around spherically symmetric self-gravitating systems,
like stars or similar astrophysical objects as well, in the Randall-Sundrum
brane-world framework. A consistent extension of this approach is developed
here, which contains modifications of both the time component and the radial
component of a spherically symmetric metric. A modified Schwarzschild geometry
is obtained as an example of its simplest application, and a new solution
potentially useful to describe stars in the brane-world is also presented.Comment: Improved version with new solutions. 11 pages, 4 figures. To be
published in CQ
Black Strings from Minimal Geometric Deformation in a Variable Tension Brane-World
We study brane-world models with variable brane tension and compute
corrections to the horizon of a black string along the extra dimension. The
four-dimensional geometry of the black string on the brane is obtained by means
of the minimal geometric deformation approach, and the bulk corrections are
then encoded in additional terms involving the covariant derivatives of the
variable brane tension. Our investigation shows that the variable brane tension
strongly affects the shape and evolution of the black string horizon along the
extra dimension, at least in a near-brane expansion. In particular, we apply
our general analysis to a model motivated by the E\"otv\"os branes, where the
variable brane tension is related to the Friedmann-Robertson-Walker brane-world
cosmology. We show that for some stages in the evolution of the universe, the
black string warped horizon collapses to a point and the black string has
correspondingly finite extent along the extra dimension. Furthermore, we show
that in the minimal geometric deformation of a black hole on the variable
tension brane, the black string has a throat along the extra dimension, whose
area tends to zero as time goes to infinity.Comment: 20 pages, 6 figure
Brane-world stars with solid crust and vacuum exterior
The minimal geometric deformation approach is employed to show the existence
of brane-world stellar distributions with vacuum Schwarzschild exterior, thus
without energy leaking from the exterior of the brane-world star into the extra
dimension. The interior satisfies all elementary criteria of physical
acceptability for a stellar solution, namely, it is regular at the origin, the
pressure and density are positive and decrease monotonically with increasing
radius, finally all energy conditions are fulfilled. A very thin solid crust
with negative radial pressure separates the interior from the exterior, having
a thickness inversely proportional to both the brane tension and the radius of the star, i.e. . This
brane-world star with Schwarzschild exterior would appear only thermally
radiating to a distant observer and be fully compatible with the stringent
constraints imposed on stellar parameters by observations of gravitational
lensing, orbital evolutions or properties of accretion disks.Comment: 20 pages, 6 figures. Improved version. To be published in Classical
and Quantum Gravit
Classical Tests of General Relativity: Brane-World Sun from Minimal Geometric Deformation
We consider a solution of the effective four-dimensional brane-world
equations, obtained from the General Relativistic Schwarzschild metric via the
principle of Minimal Geometric Deformation, and investigate the corresponding
signatures stemming from the possible existence of a warped extra dimension. In
particular, we derive bounds on an extra-dimensional parameter, closely related
with the fundamental gravitational length, from the experimental results of the
classical tests of General Relativity in the Solar system.Comment: 6 pages, slightly improved, to appear in Europhysics Letter
Quantum Reissner-Nordström geometry: Singularity and Cauchy horizon
We present a quantum description of electrically charged spherically symmetric black holes given by coherent states of gravitons in which both the central singularity and the Cauchy horizon are not realized
From black hole mimickers to black holes
We present a simple analytical model for studying the collapse of an ultracompact stellar object (regular black hole mimicker with infinite redshift surface) to form a (integrable) black hole, in the framework of general relativity. Both initial and final configurations have the same ADM mass, so the transition represents an internal redistribution of matter without emission of energy. The model, despite being quite idealized, can be viewed as a good starting point to investigate near-horizon quantum physics
Regular hairy black holes through Minkowski deformation
Static and stationary regular black holes are examined under a minimal set of
requirements consisting of (i) the existence of a well defined event horizon
and (ii) the weak energy condition for matter sourcing the geometry. We perform
our analysis by means of the gravitational decoupling approach and find hairy
solutions free of curvature singularities. We identify the matter source
producing a deformation of the Minkowski vacuum such that the maximum
deformation is the Schwarzschild solution for the static case, and the Kerr
metric for the stationary case.Comment: 8 pages, 3 figures, final version to appear in Phys.Lett.
Integración de procesos de negocio basados en servicios Web: Coreografía y satisfacción de restricciones
Los procesos de negocio en ocasiones necesitan funcionalidades adicionales que pueden alcanzarse empleando servicios del mismo dominio o de uno externo. Durante este procedimiento, los servicios web involucrados deben integrarse, de tal forma que sus funcionalidades individuales generen un comportamiento global. La coreografía de servicios web controla la secuencia de las interacciones entre los servicios durante el proceso de integración. Este artículo presenta una aproximación al modelado basado en restricciones de la coreografía de servicios web, a fin de lograr su automatización
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