We study the Page curve for eternal Garfinkle–Horowitz–Strominger dilaton black holes in four dimensional asymptotically flat spacetime by using the island paradigm. The results demonstrate that ...without the island, the entanglement entropy of Hawking radiation is proportional to time and becomes divergent at late times. While taking account of the existence of the island outside the event horizon, the entanglement entropy stops growing at late times and eventually reaches a saturation value. This value is twice of the Bekenstein–Hawking entropy and consistent with the finiteness of the von Neumann entropy of eternal black holes. Moreover, we discuss the impact of the stringy coefficient
n
and charge
Q
on the Page time and the scrambling time respectively. For the non-extremal case, the influence of the coefficient
n
on them is small compared to the influence of the charge
Q
. However, for the extremal case, the Page time and the scrambling time become divergent or near vanishing. This implies the island paradigm needs further investigation.
We study charged black hole solutions in 4-dimensional (4D) Einstein–Gauss–Bonnet–Maxwell theory to the linearized perturbation level. We first compute the shear viscosity to entropy density ratio. ...We then demonstrate how bulk causal structure analysis imposes an upper bound on the Gauss–Bonnet coupling constant in the AdS space. Causality constrains the value of Gauss–Bonnet coupling constant
α
GB
to be bounded by
α
GB
≤
0
as
D
→
4
.
A
bstract
The “pole-skipping” phenomenon reflects that the retarded Green’s function is not unique at a pole-skipping point in momentum space (
ω, k
). We explore the universality of pole-skipping in ...different geometries. In holography, near horizon analysis of the bulk equation of motion is a more straightforward way to derive a pole-skipping point. We use this method in Lifshitz, AdS
2
and Rindler geometries. We also study the complex hydrodynamic analyses and find that the dispersion relations in terms of dimensionless variables
ω
2
πT
and
k
2
πT
pass through pole-skipping points
ω
n
2
πT
k
n
2
πT
at small
ω
and
k
in the Lifshitz background. We verify that the position of the pole-skipping points does not depend on the standard quantization or alternative quantization of the boundary theory in AdS
2
×
ℝ
d−
1
geometry. In the Rindler geometry, we cannot find the corresponding Green’s function to calculate pole-skipping points because it is difficult to impose the boundary condition. However, we can still obtain “special points” near the horizon where bulk equations of motion have two incoming solutions. These “special points” correspond to the nonuniqueness of the Green’s function in physical meaning from the perspective of holography.
The pole-skipping phenomenon is a special property of the retarded Green’s function of black hole perturbations. We turn to its analog in acoustic black holes, which may relate to experiments. The ...frequencies of these special points are located at negative integer (imaginary) Matsubara frequencies
ω
=
-
i
2
π
T
n
, which are consistent with the imaginary frequencies of quasinormal modes (QNMs). This implies that the lower-half plane pole-skipping phenomena have the same physical meaning as the imaginary part of QNMs, which represents the dissipation of perturbation of acoustic black holes and is related to the instability time scale of perturbation.
A
bstract
We study the thermo-electric transport coefficients of an extended version of the Gubser-Rocha model. After reviewing the two relaxation time model from holography and studying the effect ...of the magnetic field on thermo-electric transports from hydrodynamic theory, we present a new dilatonic dyonic asymptotically AdS black hole solution. Notice that S-duality plays an important role in finding the analytic solution with the magnetic field. Using the AdS/CMT dictionary, we analyze the electric and thermo-electric transport properties of the dual field theory. The resistivity and the Hall angle are both linear in
T
for fixed
k/μ
and
B/μ
2
for low temperatures. For fixed
k/T
and
μ/T
, the electric transport coefficients are strange metallic. The magnetoresistance is approximately quadratic in
B
for various choices of parametrizations. The Nernst signal is a bell-shaped function in terms of the magnetic field even when the momentum relaxation is strong.
Page curves for accelerating black holes Yu, Ming-Hui; Ge, Xian-Hui; Lu, Cheng-Yuan
European physical journal. C, Particles and fields,
12/2023, Volume:
83, Issue:
12
Journal Article
Peer reviewed
Open access
The island paradigm for the fine-grained entropy of Hawking radiation is applied to eternal charged accelerating black holes. In the absence of the island, the entanglement entropy grows linearly and ...divergent at late times, while once the island outside the event horizon is taken into account, the unitary Page curve is reproduced naturally. The impact of the charge and the acceleration on Page curves is investigated at late times. For the Page time and the scrambling time, they both increase as the acceleration increases, while decreasing as the charge increases. In particular, neutral black holes have the largest Page time and scrambling time. It is worth noting that the Page time and the scrambling time is divergent at the extremal case, which implies that islands may be related to the causal structure of spacetime.
We explore the chaotic behavior of particle motion in a black hole with quasitopological electromagnetism. The chaos bound is found to be violated in the higher order expansion of the metric function ...and the electric potential near the horizon. We draw the Poincaré sections of particle motion corresponding to the chaos bound violated and nonviolated cases, respectively. Then we study the relationship between the "maximal" Lyapunov exponent λs defined by the static equilibrium and the Lyapunov exponent of the particle geodesic motion near the Reissner-Nordström black hole and the black hole with quasitopological electromagnetism. We find an interesting relationship between the Lyapunov exponent λph of photon's radial falling into the black hole and the maximal Lyapunov exponent λs. For the black holes whose metric function increases monotonically with radius outside horizon, this leads to λph ≥ 2λs.
Einstein–Maxwell–Gauss–Bonnet-axion theory in 4-dimensional spacetime is investigated in this paper through a “Kaluza–Klein-like” process. Dual to systems at finite temperature with background ...magnetic field on three dimensions, the four-dimensional dyonic black hole solution coupled with higher derivative terms is obtained. After the tensor-type perturbation is added, the shear viscosity to entropy density ratio is calculated at high temperature and low temperature separately. The behaviour of shear viscosity to entropy density ratio of uncharged black holes is found to be similar with that in 5-dimensional spacetime, violating the Kovtun–Starinets–Son bound as well when temperature becomes lower. In addition, the main feature of this ratio remains almost unchanged in 4 dimensions, which is characterised by
(
T
/
Δ
)
2
at low temperature
T
, with
Δ
proportional to the coefficient
β
from scalar fields. The difficulty in causal analysis is also discussed, which is mainly caused by the vanishing momentum term in equations of motion.
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