2,995 research outputs found
New attractor mechanism for spherically symmetric extremal black holes
We introduce a new attractor mechanism to find the entropy for spherically
symmetric extremal black holes. The key ingredient is to find a two-dimensional
(2D) dilaton gravity with the dilaton potential . The condition of an
attractor is given by and
and for a constant dilaton ,
these are also used to find the location of the degenerate horizon of
an extremal black hole. As a nontrivial example, we consider an extremal
regular black hole obtained from the coupled system of Einstein gravity and
nonlinear electrodynamics. The desired Bekenstein-Hawking entropy is
successfully recovered from the generalized entropy formula combined with the
2D dilaton gravity, while the entropy function approach does not work for
obtaining this entropy.Comment: 20 pages, 4 figures, Accepted for publication in Physical Review D.
This version includes revisions suggested by the refere
Critical gravity on AdS2 spacetimes
We study the critical gravity in two dimensional AdS (AdS) spacetimes,
which was obtained from the cosmological topologically massive gravity
(TMG) in three dimensions by using the Kaluza-Klein dimensional
reduction. We perform the perturbation analysis around AdS, which may
correspond to the near-horizon geometry of the extremal BTZ black hole obtained
from the TMG with identification upon uplifting three dimensions. A
massive propagating scalar mode satisfies the second-order
differential equation away from the critical point of , whose solution is
given by the Bessel functions. On the other hand, satisfies the
fourth-order equation at the critical point. We exactly solve the fourth-order
equation, and compare it with the log-gravity in two dimensions. Consequently,
the critical gravity in two dimensions could not be described by a massless
scalar and its logarithmic partner .Comment: 17 pages, 3 figure
Thermodynamic duality between RN black hole and 2D dilaton gravity
All thermodynamic quantities of the Reissner-Nordstr\"om (RN) black hole can
be obtained from the dilaton and its potential of two dimensional (2D) dilaton
gravity. The dual relations of four thermodynamic laws are also established.
Furthermore, the near-horizon thermodynamics of the extremal RN black hole is
completely described by the Jackiw-Teitelboim theory which is obtained by
perturbing around the AdS-horizon.Comment: 10 pages, 3 figures, version accepted by MPL
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