Statistical Entropy of Four-Dimensional Rotating Black Holes from Near-Horizon Geometry

Abstract We classify the necessary and sufficient conditions to obtain the near-horizon geometry of extremal supersymmetric rotating black holes embedded in 11d supergravity which are associated to rotating M2-branes. Such rotating black holes admit an AdS2 near-horizon geometry which is fibered by the transverse spacetime directions. In this paper we allow for the most general fibration over AdS2 with a flux configuration permitting rotating M2-branes. Using G-structure techniques we rewrite the conditions for supersymmetry in terms of differential equations on an eight-dimensional balanced space. The 9d compact internal space is a U(1)-fibration over this 8d base. The geometry is constrained by a master equation reminiscent of the one found in the non-rotating case. We give a Lagrangian from which the equations of motion may be derived, and show how the asymptotically AdS4 electrically charged Kerr-Newman black hole in 4d $$ \mathcal{N} $$ N = 2 supergravity is embedded in the classification. In addition, we present the conditions for the near-horizon geometry of rotating black strings in Type IIB by using dualities with the 11d setup.

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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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Black hole hair removal for N = 4 CHL models

Journal of High Energy Physics ◽

10.1007/jhep02(2021)125 ◽

2021 ◽

Vol 2021 (2) ◽

Author(s):

Subhroneel Chakrabarti ◽

Suresh Govindarajan ◽

P. Shanmugapriya ◽

Yogesh K. Srivastava ◽

Amitabh Virmani

Keyword(s):

Black Holes ◽

Black Hole ◽

Degrees Of Freedom ◽

Microscopic Analysis ◽

Flat Space ◽

Special Care ◽

Hair Removal ◽

Partition Functions ◽

Rotating Black Holes

Abstract Although BMPV black holes in flat space and in Taub-NUT space have identical near-horizon geometries, they have different indices from the microscopic analysis. For K3 compactification of type IIB theory, Sen et al. in a series of papers identified that the key to resolving this puzzle is the black hole hair modes: smooth, normalisable, bosonic and fermionic degrees of freedom living outside the horizon. In this paper, we extend their study to N = 4 CHL orbifold models. For these models, the puzzle is more challenging due to the presence of the twisted sectors. We identify hair modes in the untwisted as well as twisted sectors. We show that after removing the contributions of the hair modes from the microscopic partition functions, the 4d and 5d horizon partition functions agree. Special care is taken to present details on the smoothness analysis of hair modes for rotating black holes, thereby filling an essential gap in the literature.

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