4 research outputs found
Replica Trick Calculation for Entanglement Entropy of Static Black Hole Spacetimes
We calculate the entanglement entropy between two (maximally-extended)
spacetime regions of static black hole, seperated by horizon. As a first case,
we consider the Schwarzschild black hole, and then we extend the calculations
to the charged Reissner- Nordstrom and Schwarzschild-de Sitter black holes with
more than one horizon. The case for static and spherically-symmetric solution
to the more general F (R) gravity is also considered. The calculation of the
entanglement entropy is performed using the replica trick by obtaining the
explicit form of the metric which corresponds to the replica spacetime for each
black hole under consideration. The calculation of static and
spherically-symmetric black holes result in the entanglement entropy that
matches the Bekenstein-Hawking area law entropy.Comment: 41 pages, 12 figure
Chaos and fast scrambling delays of dyonic Kerr-Sen-AdS black hole and its ultra-spinning version
The scrambling time and its delay are calculated using holography in an
asymptotically AdS black hole solution of the gauged
Einstein-Maxwell-Dilaton-Axion (EMDA) theory, the dyonic Kerr-Sen-AdS black
hole, perturbed by rotating and charged shock waves along the equator. The
leading term of the scrambling time for a black hole with large entropy is
logarithmic in the entropy and hence supports the fast scrambling conjecture
for this black hole solution, which implies that the system under consideration
is chaotic. We also find that the instantaneous minimal Lyapunov index is
bounded by , which is analogous to the
surface gravity but for the rotating shock waves, and becomes closer to
equality for the near extremal black hole. For a small value of the AdS scale,
we found that the Lyapunov exponent can exceed the bound for a large value of
. Due to the presence of the electric and magnetic charge of the
shock waves, we also show that the scrambling process of this holographic
system is delayed by a time scale that depends on the charges of the shock
waves. The calculations also hold for the ultra-spinning version of this black
hole. The result of this paper generalizes the holographic calculations of
chaotic systems which are described by an EMDA theory in the bulk.Comment: 19 page
Localized chaos in rotating and charged AdS black holes
The butterfly velocity and the Lyapunov exponent of four-dimensional rotating
charged asymptotically AdS black holes are calculated to probe chaos using
localized rotating and charged shock waves. The localized shocks also generate
butterfly velocities which quickly vanish when we approach extremality,
indicating no entanglement spread near extremality. One of the butterfly
velocity modes is well bounded by both the speed of light and the
Schwarzschild-AdS result, while the other may become superluminal. Aside from
the logarithmic behavior of the scrambling time which indicates chaos, the
Lyapunov exponent is also positive and bounded by . The Kerr-NUT-AdS and Kerr-Sen-AdS solutions are used
as examples to attain a better understanding of the chaotic phenomena in
rotating black holes, especially the ones with extra conserved charges.Comment: 10 pages, 4 figures. Comments are welcom
Black-Body Radiation in a Uniformly Accelerated Frame
We derive Planck's radiation law in a uniformly accelerated frame expressed
in Rindler coordinates. The black-body spectrum is time-dependent and Planckian
at each instantaneous time, but it is scaled by an emissivity factor that
depends on the Rindler spatial coordinate and the acceleration magnitude. The
observer in an accelerated frame will perceive the black-body as black,
hyperblack, or grey, depending on its position with respect to the source
(moving away or towards), the acceleration magnitude, and the case of whether
it is accelerated or decelerated. For an observer accelerating away from the
source, there exists a threshold on the acceleration magnitude beyond which it
stops receiving radiation from the black-body. Since the frequency and the
number of modes in Planck's law evolve over time, the spectrum is continuously
red or blue-shifted towards lower (or higher) frequencies as time progresses,
and the radiation modes (photons) could be created or annihilated, depending on
the observer's position and its acceleration or deceleration relative to the
source of radiation.Comment: 21 pages, 14 figure