241 research outputs found
Dynamical evolution of a vector field perturbation coupling to Einstein tensor
We have investigated the wave dynamics of a vector field perturbation
coupling to Einstein tensor in the four-dimensional Reissner-Nordstr\"{o}m
black hole spacetime. Our results show that besides the dependence on the
coupling between the vector field and Einstein tensor, the wave dynamic
equation of the vector field perturbation strongly depends on the parity of the
perturbation itself, which is quite different from that of the usual vector
field perturbation without the coupling in the four-dimensional spacetime.
Moreover, we also find that the vector field perturbation with odd parity grows
with exponential rate if the coupling strength is stronger than certain a
critical value. However, the vector field perturbation with even parity always
decays in the Reissner-Nordstr\"{o}m black hole spacetime.Comment: 19 pages; 10 figures. Title is changed and the mistakes are
corrected. Accepted by PRD for publication. arXiv admin note: text overlap
with arXiv:1307.745
Rotating charged black hole with Weyl corrections
We present firstly a four-dimensional spherical symmetric black hole with
small Weyl corrections and find that with increasing Weyl corrections the
region of the event horizon existence for the black hole in the parameter space
increases for the negative Weyl coupling parameter and decreases for the
positive one. Moreover, we also obtain a rotating charged black hole with weak
Weyl corrections by the method of complex coordinate transformation. Our
results show that the sign of Weyl coupling parameter yields the
different spatial topology of the event horizons for the black hole with its
parameters lied in some special regions in the parameter space. We also analyze
the dependence of the ergosphere on the Weyl coupling parameter and
find that with the increase of the Weyl corrections the ergosphere in the
equatorial plane becomes thick for a black hole with , but becomes
thin in the case with , which means that the energy extraction become
easier in the background of a black hole with the positive Weyl coupling
parameter, but more difficult in the background of a black hole with the
negative one.Comment: 16 pages, 9 figures, corrected version accepted by Phys. Rev.
Strong gravitational lensing for the photons coupled to Weyl tensor in a Schwarzschild black hole spacetime
We have investigated the strong gravitational lensing for the photons coupled
to Weyl tensor in a Schwarzschild black hole spacetime. We find that in the
four-dimensional black hole spacetime the equation of motion of the photons
depends not only on the coupling between photon and Weyl tensor, but also on
the polarization direction of the photons. It is quite different from that in
the case of the usual photon without coupling to Weyl tensor in which the
equation of motion is independent of the polarization of the photon. Moreover,
we find that the coupling and the polarization direction modify the properties
of the photon sphere, the deflection angle, the coefficients in strong field
lensing, and the observational gravitational lensing variables. Combining with
the supermassive central object in our Galaxy, we estimated three observables
in the strong gravitational lensing for the photons coupled to Weyl tensor.Comment: 19 pages and 7 figures; A corrected version for publication in JCA
Asymptotic quasinormal modes of a coupled scalar field in the Garfinkle-Horowitz-Strominger dilaton spacetime
The analytic forms of the asymptotic quasinormal frequencies of a coupled
scalar field in the Garfinkle-Horowitz-Strominger dilaton spacetime is
investigated by using the monodromy technique proposed by Motl and Neitzke. It
is found that the asymptotic quasinormal frequencies depend not only on the
structure parameters of the background spacetime, but also on the coupling
between the scalar fields and gravitational field. Moreover, our results show
that only in the minimal couple case, i.e., tends zero, the real parts of
the asymptotic quasinormal frequencies agrees with the Hod's conjecture,
.Comment: 6 pages, 1 figur
Dark energy interacting with dark matter and unparticle
We study dynamical behaviors of the dark energy models interacting with dark
matter and unparticle in the standard flat FRW cosmology. We considered four
different interacting models and examined the stability of the critical points.
We find that there exist late-time scaling attractors corresponding to an
accelerating Universe and the alleviation of the coincidence problem depends on
the choice of parameters in the models.Comment: 16 pages, 7 figure
Gravitational field of a slowly rotating black hole with phantom global monopole
We present a slowly rotating black hole with phantom global monopole by
solving Einstein's field equation and find that presence of global monopole
changes the structure of black hole. The metric coefficient
contains hypergeometric function of the polar coordinate , which is more
complex than that in the usual slowly rotating black hole. The energy scale of
symmetry breaking affects the black hole horizon and a deficit solid
angle. Especially, the solid angle is surplus rather than deficit for a black
hole with the phantom global monopole. We also study the correction originating
from the global monopole to the angular velocity of the horizon , the
Kepler's third law, the innermost stable circular orbit and the radiative
efficiency in the thin accretion disk model. Our results also show
that for the phantom black hole the radiative efficiency is positive
only for the case . The threshold value increases
with the rotation parameter .Comment: 14 pages, 6 figure
Shadow casted by a Konoplya-Zhidenko rotating non-Kerr black hole
We have investigated the shadow of a Konoplya-Zhidenko rotating non-Kerr
black hole with an extra deformation parameter. The spacetime structure arising
from the deformed parameter affects sharply the black hole shadow. With the
increase of the deformation parameter, the size of the shadow of black hole
increase and its shape becomes more rounded for arbitrary rotation parameter.
The D-shape shadow of black hole emerges only in the case
with the proper deformation parameter. Especially, the
black hole shadow possesses a cusp shape with small eye lashes in the cases
with , and the shadow becomes less cuspidal with the increase of the
deformation parameter. Our result show that the presence of the deformation
parameter yields a series of significant patterns for the shadow casted by a
Konoplya-Zhidenko rotating non-Kerr black hole.Comment: 12 pages, 6 figures, some typos are corrected and some references
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Chaotic motion of particles in the accelerating and rotating black holes spacetime
We have investigated the motion of timelike particles along geodesic in the
background of accelerating and rotating black hole spacetime. We confirmed that
the chaos exists in the geodesic motion of the particles by Poincar\'e
sections, the power spectrum, the fast Lyapunov exponent indicator and the
bifurcation diagram. Moreover, we probe the effects of the acceleration and
rotation parameters on the chaotic behavior of a timelike geodesic particle in
the black hole spacetime. Our results show that the acceleration brings richer
physics for the geodesic motion of particles.Comment: 20 pages, 12 figures, Accepted by JHEP for publicatio
Analytical expressions for greybody factor and dynamic evolution for scalar field in Ho\v{r}ava-Lifshitz black hole
We investigate the propagation and evolution for a massless scalar field in
the background of Ho\v{r}ava-Lifshitz black hole with the
condition of detailed balance. We fortunately obtain an exact solution for the
Klein-Gordon equation. Then, we find an analytical expression for the greybody
factor which is valid for any frequency; and also exactly show that the
perturbation decays without any oscillation. All of these can help us to
understand more about the Ho\v{r}ava-Lifshitz gravity.Comment: 13 pages, 4 figures, Accepted for publication in PR
Repulsive effect for the unbound high energy particles along the rotation axis in the Kerr-Taub-NUT spacetime
We have investigated the acceleration of the unbound high energy particles
moving along the rotation axis in the Kerr-Taub-NUT spacetime, and then study
the dependence of the repulsive effects on the NUT charge for the particles in
the spacetime. Whether the repulsive effects with the NUT charge become
stronger depends on the Carter constant, the position and velocity of the
particles themselves. We also present numerically the changes of the observable
velocity and acceleration with the NUT charge for the unbound particles in the
Kerr-Taub-NUT spacetime.Comment: 15 pages, 4 figure
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