A model problem for quasinormal ringdown of asymptotically flat or extremal black holes

Abstract Four-dimensional $$ \mathcal{N} $$ N = 4 supersymmetric Yang-Mills theory, at a point on the Coulomb branch where SU(N) gauge symmetry is spontaneously broken to SU(N − 1) × U(1), admits BPS solitons describing a spherical shell of electric and/or magnetic charges enclosing a region of unbroken gauge symmetry. These solitons have been proposed as gauge theory models for certain features of asymptotically flat extremal black holes. In the ’t Hooft large N limit with large ’t Hooft coupling, these solitons are holographically dual to certain probe D3-branes in the AdS5 × S5 solution of type IIB supergravity. By studying linearised perturbations of these D3-branes, we show that the solitons support quasinormal modes with a spectrum of frequencies sharing both qualitative and quantitative features with asymptotically flat extremal black holes.

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Quantum BMS transformations in conformally flat space-times and holography

Journal of High Energy Physics ◽

10.1007/jhep12(2020)102 ◽

2020 ◽

Vol 2020 (12) ◽

Author(s):

Laura Donnay ◽

Gaston Giribet ◽

Felipe Rosso

Keyword(s):

Hilbert Space ◽

Black Holes ◽

Flat Space ◽

Conformal Killing ◽

Conformally Flat ◽

Asymptotically Flat ◽

Conformal Killing Vectors ◽

Classical Gravity ◽

Holographic Description ◽

Extremal Black Holes

Abstract We define and study asymptotic Killing and conformal Killing vectors in d-dimensional Minkowski, (A)dS, ℝ × Sd−1 and AdS2× Sd−2. We construct the associated quantum charges for an arbitrary CFT and show they satisfy a closed algebra that includes the BMS as a sub-algebra (i.e. supertranslations and superrotations) plus a novel transformation we call ‘superdilations’. We study representations of this algebra in the Hilbert space of the CFT, as well as the action of the finite transformations obtained by exponentiating the charges. In the context of the AdS/CFT correspondence, we propose a bulk holographic description in semi-classical gravity that reproduces the results obtained from CFT computations. We discuss the implications of our results regarding quantum hairs of asymptotically flat (near-)extremal black holes.

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Special Vinberg cones and the entropy of BPS extremal black holes

Journal of High Energy Physics ◽

10.1007/jhep11(2021)100 ◽

2021 ◽

Vol 2021 (11) ◽

Author(s):

Dmitri V. Alekseevsky ◽

Alessio Marrani ◽

Andrea Spiro

Keyword(s):

Black Holes ◽

Symmetric Space ◽

Explicit Expression ◽

Spherically Symmetric ◽

Quadratic Map ◽

Asymptotically Flat ◽

Homogeneous Cones ◽

Extremal Black Holes

Abstract We consider the static, spherically symmetric and asymptotically flat BPS extremal black holes in ungauged N = 2 D = 4 supergravity theories, in which the scalar manifold of the vector multiplets is homogeneous. By a result of Shmakova on the BPS attractor equations, the entropy of this kind of black holes can be expressed only in terms of their electric and magnetic charges, provided that the inverse of a certain quadratic map (uniquely determined by the prepotential of the theory) is given. This inverse was previously known just for the cases in which the scalar manifold of the theory is a homogeneous symmetric space. In this paper we use Vinberg’s theory of homogeneous cones to determine an explicit expression for such an inverse, under the assumption that the scalar manifold is homogeneous, but not necessarily symmetric. As immediate consequence, we get a formula for the entropy of BPS black holes that holds in any model of N = 2 supergravity with homogeneous scalar manifold.

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Entanglement entropy of asymptotically flat non-extremal and extremal black holes with an island

The European Physical Journal C ◽

10.1140/epjc/s10052-021-09680-x ◽

2021 ◽

Vol 81 (10) ◽

Author(s):

Wontae Kim ◽

Mungon Nam

Keyword(s):

Black Holes ◽

Black Hole ◽

Entanglement Entropy ◽

Heat Bath ◽

Extremal Black Hole ◽

Curvature Singularity ◽

Island Rule ◽

Generalized Entropy ◽

Asymptotically Flat ◽

Extremal Black Holes

AbstractThe island rule for the entanglement entropy is applied to an eternal Reissner–Nordström black hole. The key ingredient is that the black hole is assumed to be in thermal equilibrium with a heat bath of an arbitrary temperature and so the generalized entropy is treated as being off-shell. Taking the on-shell condition to the off-shell generalized entropy, we find the generalized entropy and then obtain the entanglement entropy following the island rule. For the non-extremal black hole, the entanglement entropy grows linearly in time and can be saturated after the Page time as expected. The entanglement entropy also has a well-defined Schwarzschild limit. In the extremal black hole, the island prescription provides a logarithmically growing entanglement entropy in time and a constant entanglement entropy after the Page time. In the extremal black hole, the boundary of the island hits the curvature singularity where the semi-classical approximations appear invalid. To avoid encountering the curvature singularity, we apply this procedure to the Hayward black hole regular at the origin. Consequently, the presence of the island in extremal black holes can provide a finite entanglement entropy, which might imply non-trivial vacuum configurations of extremal black holes.

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Extremal black holes that are not extremal: maximal warm holes

Journal of High Energy Physics ◽

10.1007/jhep01(2022)064 ◽

2022 ◽

Vol 2022 (1) ◽

Author(s):

Óscar J. C. Dias ◽

Gary T. Horowitz ◽

Jorge E. Santos

Keyword(s):

Black Holes ◽

Black Hole ◽

Hawking Temperature ◽

Charged Scalar ◽

Asymptotically Flat ◽

Charged Black Holes ◽

Maximum Charge ◽

Scalar Hair ◽

Hairy Black Hole ◽

Extremal Black Holes

Abstract We study a family of four-dimensional, asymptotically flat, charged black holes that develop (charged) scalar hair as one increases their charge at fixed mass. Surprisingly, the maximum charge for given mass is a nonsingular hairy black hole with nonzero Hawking temperature. The implications for Hawking evaporation are discussed.

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Islands and stretched horizon

Journal of High Energy Physics ◽

10.1007/jhep07(2021)051 ◽

2021 ◽

Vol 2021 (7) ◽

Author(s):

Yoshinori Matsuo

Keyword(s):

Black Holes ◽

Black Hole ◽

Hawking Radiation ◽

Entanglement Entropy ◽

Total System ◽

Island Rule ◽

Asymptotically Flat ◽

Flat Spacetime ◽

Ads Spacetime ◽

Hole Geometry

Abstract Recently it was proposed that the entanglement entropy of the Hawking radiation contains the information of a region including the interior of the event horizon, which is called “island.” In studies of the entanglement entropy of the Hawking radiation, the total system in the black hole geometry is separated into the Hawking radiation and black hole. In this paper, we study the entanglement entropy of the black hole in the asymptotically flat Schwarzschild spacetime. Consistency with the island rule for the Hawking radiation implies that the information of the black hole is located in a different region than the island. We found an instability of the island in the calculation of the entanglement entropy of the region outside a surface near the horizon. This implies that the region contains all the information of the total system and the information of the black hole is localized on the surface. Thus the surface would be interpreted as the stretched horizon. This structure also resembles black holes in the AdS spacetime with an auxiliary flat spacetime, where the information of the black hole is localized at the interface between the AdS spacetime and the flat spacetime.

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New non-extremal and BPS hairy black holes in gauged $$ \mathcal{N} $$ = 2 and $$ \mathcal{N} $$ = 8 supergravity

Journal of High Energy Physics ◽

10.1007/jhep04(2021)047 ◽

2021 ◽

Vol 2021 (4) ◽

Author(s):

Andres Anabalon ◽

Dumitru Astefanesei ◽

Antonio Gallerati ◽

Mario Trigiante

Keyword(s):

Black Holes ◽

Black Hole ◽

Boundary Conditions ◽

Charged Black Hole ◽

Dual Theory ◽

Real Numbers ◽

Hairy Black Holes ◽

Interpolation Parameter ◽

Black Hole Solutions ◽

Extremal Black Holes

Abstract In this article we study a family of four-dimensional, $$ \mathcal{N} $$ N = 2 supergravity theories that interpolates between all the single dilaton truncations of the SO(8) gauged $$ \mathcal{N} $$ N = 8 supergravity. In this infinitely many theories characterized by two real numbers — the interpolation parameter and the dyonic “angle” of the gauging — we construct non-extremal electrically or magnetically charged black hole solutions and their supersymmetric limits. All the supersymmetric black holes have non-singular horizons with spherical, hyperbolic or planar topology. Some of these supersymmetric and non-extremal black holes are new examples in the $$ \mathcal{N} $$ N = 8 theory that do not belong to the STU model. We compute the asymptotic charges, thermodynamics and boundary conditions of these black holes and show that all of them, except one, introduce a triple trace deformation in the dual theory.

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Slow scrambling in extremal BTZ and microstate geometries

Journal of High Energy Physics ◽

10.1007/jhep03(2021)020 ◽

2021 ◽

Vol 2021 (3) ◽

Author(s):

Ben Craps ◽

Marine De Clerck ◽

Philip Hacker ◽

Kévin Nguyen ◽

Charles Rabideau

Keyword(s):

Field Theory ◽

Black Holes ◽

Degrees Of Freedom ◽

Average Power ◽

Nonzero Temperature ◽

Time Intervals ◽

Conformal Field ◽

Btz Black Holes ◽

The Right ◽

Extremal Black Holes

Abstract Out-of-time-order correlators (OTOCs) that capture maximally chaotic properties of a black hole are determined by scattering processes near the horizon. This prompts the question to what extent OTOCs display chaotic behaviour in horizonless microstate geometries. This question is complicated by the fact that Lyapunov growth of OTOCs requires nonzero temperature, whereas constructions of microstate geometries have been mostly restricted to extremal black holes.In this paper, we compute OTOCs for a class of extremal black holes, namely maximally rotating BTZ black holes, and show that on average they display “slow scrambling”, characterized by cubic (rather than exponential) growth. Superposed on this average power-law growth is a sawtooth pattern, whose steep parts correspond to brief periods of Lyapunov growth associated to the nonzero temperature of the right-moving degrees of freedom in a dual conformal field theory.Next we study the extent to which these OTOCs are modified in certain “superstrata”, horizonless microstate geometries corresponding to these black holes. Rather than an infinite throat ending on a horizon, these geometries have a very deep but finite throat ending in a cap. We find that the superstrata display the same slow scrambling as maximally rotating BTZ black holes, except that for large enough time intervals the growth of the OTOC is cut off by effects related to the cap region, some of which we evaluate explicitly.

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Observations of Hawking radiation: the Page curve and baby universes

Journal of High Energy Physics ◽

10.1007/jhep04(2021)272 ◽

2021 ◽

Vol 2021 (4) ◽

Author(s):

Donald Marolf ◽

Henry Maxfield

Keyword(s):

Black Holes ◽

Quantum Systems ◽

Late Time ◽

Asymptotically Flat ◽

Black Hole Information ◽

Flat Spacetimes ◽

The Cost ◽

Baby Universes ◽

Time Extrapolation ◽

Asymptotic Observers

AbstractWe reformulate recent insights into black hole information in a manner emphasizing operationally-defined notions of entropy, Lorentz-signature descriptions, and asymptotically flat spacetimes. With the help of replica wormholes, we find that experiments of asymptotic observers are consistent with black holes as unitary quantum systems, with density of states given by the Bekenstein-Hawking formula. However, this comes at the cost of superselection sectors associated with the state of baby universes. Spacetimes studied by Polchinski and Strominger in 1994 provide a simple illustration of the associated concepts and techniques, and we argue them to be a natural late-time extrapolation of replica wormholes. The work aims to be self-contained and, in particular, to be accessible to readers who have not yet mastered earlier formulations of the ideas above.

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Uptunneling to de Sitter

Journal of High Energy Physics ◽

10.1007/jhep09(2020)070 ◽

2020 ◽

Vol 2020 (9) ◽

Author(s):

Mehrdad Mirbabayi

Keyword(s):

Black Holes ◽

Black Hole ◽

False Vacuum ◽

De Sitter ◽

Dimensional Theory ◽

Hole Geometry ◽

Horizon Geometry ◽

Two Sides ◽

Extremal Black Holes

Abstract We propose a Euclidean preparation of an asymptotically AdS2 spacetime that contains an inflating dS2 bubble. The setup can be embedded in a four dimensional theory with a Minkowski vacuum and a false vacuum. AdS2 approximates the near horizon geometry of a two-sided near-extremal Reissner-Nordström black hole, and the two sides can connect to the same Minkowski asymptotics to form a topologically nontrivial worm- hole geometry. Likewise, in the false vacuum the near-horizon geometry of near-extremal black holes is approximately dS2 times 2-sphere. We interpret the Euclidean solution as describing the decay of an excitation inside the wormhole to a false vacuum bubble. The result is an inflating region inside a non-traversable asymptotically Minkowski wormhole.

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