2,281 research outputs found
Thermodynamics of an Evaporating Schwarzschild Black Hole in Noncommutative Space
We investigate the effects of space noncommutativity and the generalized
uncertainty principle on the thermodynamics of a radiating Schwarzschild black
hole. We show that evaporation process is in such a way that black hole reaches
to a maximum temperature before its final stage of evolution and then cools
down to a nonsingular remnant with zero temperature and entropy. We compare our
results with more reliable results of string theory. This comparison Shows that
GUP and space noncommutativity are similar concepts at least from view point of
black hole thermodynamics.Comment: 15 Pages, 2 Figures, revised and refernces adde
Entropic force and its cosmological implications
We investigate a possibility of realizing the entropic force into the
cosmology. A main issue is how the holographic screen is implemented in the
Newtonian cosmology. Contrary to the relativistic realization of Friedmann
equations, we do not clarify the connection between Newtonian cosmology and
entropic force because there is no way of implementing the holographic screen
in the Newtonian cosmology.Comment: 16 pages, no figures, version "Accepted for publication in
Astrophysics & Space Science
Quasinormal modes and hidden conformal symmetry in the Reissner-Nordstrom black hole
It is shown that the scalar wave equation in the near-horizon limit respects
a hidden SL(2,R) invariance in the Reissner-Nordstrom (RN) black hole
spacetimes. We use the SL(2,R) symmetry to determine algebraically the purely
imaginary quasinormal frequencies of the RN black hole. We confirm that these
are exactly quasinormal modes of scalar perturbation around the near-extremal
black hole.Comment: 17 pages, 1 figure, version to appear in EPJ
Nonpropagation of massive mode on AdS2 in topologically massive gravity
Making use of Achucarro-Ortiz (AO) type of dimensional reduction, we study
the topologically massive gravity with a negative cosmological constant on AdS2
spacetimes. For a constant dilaton, this two-dimensional model also admits
three AdS2 vacuum solutions, which are related to two AdS3 and warped AdS3
backgrounds with an identification upon uplifting three dimensions. We carry
out the perturbation analysis around these backgrounds to find what is a
physically propagating field. However, it turns out that there is no
propagating massive mode on AdS2 background, in contrast to the Kaluza-Klein
(KK) type of dimensional reduction. We note that two dimensionally reduced
actions are different and thus, the non-equivalence of their on-shell
amplitudes is obtained.Comment: 19 pages, version to appear in EPJ
Exactly Soluble Quantum Wormhole in Two Dimensions
We are presenting a quantum traversable wormhole in an exactly soluble
two-dimensional model. This is different from previous works since the exotic
negative energy that supports the wormhole is generated from the quantization
of classical energy-momentum tensors. This explicit illustration shows the
quantum-mechanical energy can be used as a candidate for the exotic source. As
for the traversability, after a particle travels through the wormhole, the
static initial wormhole geometry gets a back reaction which spoils the wormhole
structure. However, it may still maintain the initial structure along with the
appropriate boundary condition.Comment: v1. 13 pages, 1 figure, REVTeX3; v2. 1 Ref. added, REVTeX4, to appear
in Phys. Rev.
Slowly rotating black holes in the Horava-Lifshitz gravity
We investigate slowly rotating black holes in the Ho\v{r}ava-Lifshitz (HL)
gravity. For and , we find a slowly rotating black
hole of the Kehagias-Sfetsos solution in asymptotically flat spacetimes. We
discuss their thermodynamic properties by computing mass, temperature, angular
momentum, and angular velocity on the horizon.Comment: 12 pages, no figures, version to appear in EPJ
Does entropic force always imply the Newtonian force law?
We study the entropic force by introducing a bound between
entropy and area which was derived by imposing the non-gravitational collapse
condition. In this case, applying a modified entropic force to this system does
not lead to the Newtonian force law.Comment: 11 pages, version to appear in EPJ
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