scholarly journals Horizon acoustics of the GHS black hole and the spectrum of AdS2

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Achilleas P. Porfyriadis ◽  
Grant N. Remmen
Keyword(s):  
Black Hole ◽  
Effective Potentials ◽  
Effective Masses ◽  
Perturbation Problem ◽  
Novel Structure ◽  
Boundary Operators ◽  
Horizon Limit ◽  
Conformal Quantum Mechanics ◽  
Dilaton Coupling ◽  
Ghs Black Hole

Abstract We uncover a novel structure in Einstein-Maxwell-dilaton gravity: an AdS2 × S2 solution in string frame, which can be obtained by a near-horizon limit of the extreme GHS black hole with dilaton coupling λ ≠ 1. Unlike the Bertotti-Robinson spacetime, our solution has independent length scales for the AdS2 and S2, with ratio controlled by λ. We solve the perturbation problem for this solution, finding the independently propagating towers of states in terms of superpositions of gravitons, photons, and dilatons and their associated effective potentials. These potentials describe modes obeying conformal quantum mechanics, with couplings that we compute, and can be recast as giving the spectrum of the effective masses of the modes. By dictating the conformal weights of boundary operators, this spectrum provides crucial data for any future construction of a holographic dual to these AdS2 × S2 configurations.

scholarly journals The primordial black hole formation criterion re-examined: Parametrisation, timing and the choice of window function

2019 ◽  
Vol 29 (02) ◽  
pp. 2030002 ◽  
Author(s):  
Sam Young
Keyword(s):  
Black Hole ◽  
Density Perturbation ◽  
Density Contrast ◽  
Smoothing Function ◽  
Primordial Black Hole ◽  
Curvature Perturbation ◽  
Order Of Magnitude ◽  
Horizon Limit ◽  
First Time ◽  
Peak Value

In this paper, the criterion used to determine whether a density perturbation will collapse to form a primordial black hole (PBH) is re-examined in respect of its use to determine the abundance of PBHs. There is particular focus on which parameter to use, the time at which the abundance should be calculated, and the use of different smoothing functions. It is concluded that, with the tools currently available, the smoothed density contrast should be used rather than the peak value, and should be calculated from the time-independent component of the density contrast in the super-horizon limit (long before perturbations enter the horizon) rather than at horizon crossing. For the first time, the effect of the choice of smoothing function upon the formation criterion is calculated, and, for a given abundance of PBHs, it is found that the uncertainty in the amplitude of the power spectrum due to this is [Formula: see text], an order of magnitude smaller than that suggested by previous calculations. The relation between the formation criterion stated in terms of the density contrast and the curvature perturbation [Formula: see text] is also discussed.

scholarly journals The near-horizon limit of the extreme rotating d   5 black hole as a homogeneous spacetime

2003 ◽  
Vol 20 (3) ◽  
pp. 423-429 ◽  
Author(s):  
Natxo Alonso-Alberca ◽  
Ernesto Lozano-Tellechea ◽  
Tom s Ort n
Keyword(s):  
Black Hole ◽  
Horizon Limit

scholarly journals DISCUSSION ON SOME CHARACTERISTICS OF CHARGED BRANE-WORLD BLACK HOLES

2009 ◽  
Vol 24 (04) ◽  
pp. 719-739 ◽  
Author(s):  
M. KALAM ◽  
F. RAHAMAN ◽  
A. GHOSH ◽  
B. RAYCHAUDHURI
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gravitational Field ◽  
Scalar Field ◽  
Brane World ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Effective Potentials ◽  
Test Particles ◽  
Jacobi Formalism

Several physical natures of charged brane-world black holes are investigated. Firstly, the timelike and null geodesics of the charged brane-world black holes are presented. We also analyze all the possible motions by plotting the effective potentials for various parameters for circular and radial geodesics. Secondly, we investigate the motion of test particles in the gravitational field of the charged brane-world black holes using the Hamilton–Jacobi formalism. We consider charged and uncharged test particles and examine their behavior in both static and nonstatic cases. Thirdly, the thermodynamics of the charged brane-world black holes are studied. Finally, it is shown that there is no phenomenon of superradiance for an incident massless scalar field for such a black hole.

scholarly journals Acceleration radiation of an atom freely falling into a Kerr black hole and near-horizon conformal quantum mechanics

2021 ◽  
Vol 104 (6) ◽  
Author(s):  
A. Azizi ◽  
H. E. Camblong ◽  
A. Chakraborty ◽  
C. R. Ordóñez ◽  
M. O. Scully
Keyword(s):  
Black Hole ◽  
Quantum Mechanics ◽  
Kerr Black Hole ◽  
Conformal Quantum Mechanics

scholarly journals Near-horizon limit of the charged BTZ black hole and AdS2quantum gravity

2008 ◽  
Vol 2008 (07) ◽  
pp. 131-131 ◽  
Author(s):  
Mariano Cadoni ◽  
Mohammad R Setare
Keyword(s):  
Black Hole ◽  
Btz Black Hole ◽  
Horizon Limit

scholarly journals NEAR EXTREMAL BLACK HOLE ENTROPY AS ENTANGLEMENT ENTROPY VIA AdS2/CFT1

2008 ◽  
Vol 23 (14n15) ◽  
pp. 2229-2230
Author(s):  
TATSUO AZEYANAGI
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Quantum Mechanics ◽  
Entanglement Entropy ◽  
Black Hole Entropy ◽  
Extremal Black Hole ◽  
Conformal Quantum Mechanics ◽  
Extremal Black Holes

We holographically derive entropy of (near) extremal black holes as entanglement entropy of conformal quantum mechanics(CQM) living in two boundaries of AdS2.

scholarly journals Note on constants of motion in conformal mechanics associated with near horizon extremal Myers–Perry black holes

2017 ◽  
Vol 32 (27) ◽  
pp. 1750144 ◽  
Author(s):  
Hovhannes Demirchian
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Separation Of Variables ◽  
Integrals Of Motion ◽  
Cartesian Coordinates ◽  
Ellipsoidal Coordinates ◽  
Constants Of Motion ◽  
Rotation Parameters ◽  
Horizon Limit ◽  
Explicit Expressions

We investigate dynamics of probe particles moving in the near-horizon limit of (2N + 1)-dimensional extremal Myers–Perry black hole (in the cases of N = 3, 4, 5) with arbitrary rotation parameters. Very recently it has been shown in [T. Hakobyan, A. Nersessian and M. M. Sheikh-Jabbari, Phys. Lett. B 772, 586 (2017)] that in the most general cases with non-equal nonvanishing rotational parameters the system admits separation of variables in N-dimensional ellipsoidal coordinates. We wrote down the explicit expressions of Liouville integrals of motion, given in the above-mentioned reference in ellipsoidal coordinates, in initial “Cartesian” coordinates in seven, nine and eleven dimensions, and found that these expressions hold in any dimension. Then, taking the limit where all of the rotational parameters are equal, we reveal that each of these N − 1 integrals of motion results in the Hamiltonian of the spherical mechanics of a (2N + 1)-dimensional MP black hole with equal nonvanishing rotational parameters.

scholarly journals The geodesics structure of Schwarzschild black hole immersed in an electromagnetic universe

2017 ◽  
Vol 26 (14) ◽  
pp. 1750169 ◽  
Author(s):  
A. Al-Badawi ◽  
M. Q. Owaidat ◽  
S. Tarawneh
Keyword(s):  
Black Hole ◽  
Analytical Solution ◽  
Exact Analytical Solution ◽  
Proper Time ◽  
Massive Particle ◽  
Schwarzschild Black Hole ◽  
Circular Orbits ◽  
Schwarzschild Metric ◽  
Effective Potentials ◽  
Em Field

The geodesic equations are considered in a spacetime that represents a Schwarzschild metric coupled to a uniform external electromagnetic (em) field. Due to the em field horizon shrinks and geodesics are modified. By analyzing the behavior of the effective potentials for the massless and massive particle we study the radial and circular trajectories. Radial geodesics for both photons and particles are solved exactly. It is shown that a particle that falls toward the horizon in a finite proper time slows down so that the particle reaches the singularity slower than Schwarzschild case. Timelike and null circular geodesics are investigated. We have shown that, there are no stable circular orbits for photons, however stable and unstable second-kind orbits exist for the massive particle. An exact analytical solution for the innermost stable circular orbits (ISCO) has been obtained. It has been shown that the radius of the ISCO shrinks due to the presence of the em field.

scholarly journals BCFT entanglement entropy at large central charge and the black hole interior

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
James Sully ◽  
Mark Van Raamsdonk ◽  
David Wakeham
Keyword(s):  
Black Hole ◽  
Phase Transitions ◽  
Single Channel ◽  
Central Charge ◽  
Black Hole Physics ◽  
Entanglement Entropy ◽  
Conformal Field ◽  
Boundary Operators ◽  
Black Hole Interior ◽  
Twist Operators

Abstract In this note, we consider entanglement and Renyi entropies for spatial subsystems of a boundary conformal field theory (BCFT) or of a CFT in a state constructed using a Euclidean BCFT path integral. Holographic calculations suggest that these entropies undergo phase transitions as a function of time or parameters describing the subsystem; these arise from a change in topology of the RT surface. In recent applications to black hole physics, such transitions have been seen to govern whether or not the bulk entanglement wedge of a (B)CFT region includes a portion of the black hole interior and have played a crucial role in understanding the semiclassical origin of the Page curve for evaporating black holes.In this paper, we reproduce these holographic results via direct (B)CFT calculations. Using the replica method, the entropies are related to correlation functions of twist operators in a Euclidean BCFT. These correlations functions can be expanded in various channels involving intermediate bulk or boundary operators. Under certain sparseness conditions on the spectrum and OPE coefficients of bulk and boundary operators, we show that the twist correlators are dominated by the vacuum block in a single channel, with the relevant channel depending on the position of the twists. These transitions between channels lead to the holographically observed phase transitions in entropies.

scholarly journals Six-point functions and collisions in the black hole interior

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Felix M. Haehl ◽  
Alexandre Streicher ◽  
Ying Zhao
Keyword(s):  
Black Hole ◽  
Three Dimensional ◽  
Quantum Circuits ◽  
Late Time ◽  
Factorization Property ◽  
Boundary Operators ◽  
Dimensional Gravity ◽  
Black Hole Interior ◽  
Left And Right ◽  
Extract Information

Abstract In the eternal AdS black hole geometry, we consider two signals sent from the boundaries into the black hole interior shared between the two asymptotic regions. We compute three different out-of-time-order six-point functions to quantify various properties of the collision of these signals behind the horizons: (i) We diagnose the strength of the collision by probing the two-signal state on a late time slice with boundary operators. (ii) We quantify two-sided operator growth, which provides a dual description of the signals meeting in the black hole interior, in terms of the quantum butterfly effect and quantum circuits. (iii) We consider an explicit coupling between the left and right CFTs to make the wormhole traversable and extract information about the collision product from behind the horizon. At a technical level, our results rely on the method of eikonal resummation to obtain the relevant gravitational contributions to Lorentzian six-point functions at all orders in the GN-expansion. We observe that such correlation functions display an intriguing factorization property. We corroborate these results with geodesic computations of six-point functions in two- and three-dimensional gravity.

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