Cosmic footballs from superrotations

Adjei, Eugene; Donnelly, William J.; Py, Victor; Speranza, Antony J.

doi:10.1088/1361-6382/ab74f6

Cited by 24 publications

(32 citation statements)

References 44 publications

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“…In particular, the coefficient appearing on the right-hand side is related to the surface gravity κ of the black hole, given by 2κ = F (r s ), so that 2r s As described in section 3, local conformal transformations naturally emerge in the discussion of the BMS group. Except for global SL(2, C) transformations which correspond to the action of the Lorentz group (boost and rotations), other general holomorphic transformations will have branch cuts and/or divergences [71,87].…”

Section: Jhep02(2021)038mentioning

confidence: 99%

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Super-Hawking radiation

Ferreira

Heissenberg

2021

J. High Energ. Phys.

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We discuss modifications to the Hawking spectrum that arise when the asymptotic states are supertranslated or superrotated. For supertranslations we find nontrivial off-diagonal phases in the two-point correlator although the emission spectrum is eventually left unchanged, as previously pointed out in the literature. In contrast, superrotations give rise to modifications which manifest themselves in the emission spectrum and depend nontrivially on the associated conformal factor at future null infinity. We study Lorentz boosts and a class of superrotations whose conformal factors do not depend on the azimuthal angle on the celestial sphere and whose singularities at the north and south poles have been associated to the presence of a cosmic string. In spite of such singularities, superrotations still lead to finite spectral emission rates of particles and energy which display a distinctive power-law behavior at high frequencies for each angular momentum state. The integrated particle emission rate and emitted power, on the contrary, while finite for boosts, do exhibit ultraviolet divergences for superrotations, between logarithmic and quadratic. Such divergences can be ascribed to modes with support along the cosmic string. In the logarithimic case, corresponding to a superrotation which covers the sphere twice, the total power emitted still presents the Stefan-Boltzmann form but with an effective area which diverges logarithmically in the ultraviolet.

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Section: Jhep02(2021)038mentioning

confidence: 99%

“…As a result, they preserve asymptotic flatness only locally, while they break it at the global level. Point singularities due to superrotations have been related to the appearance of cosmic strings [70] or to an effective deformation of the celestial sphere to an elongated object, a "cosmic football" [71].…”

Section: Introductionmentioning

confidence: 99%

Super-Hawking radiation

Ferreira

Heissenberg

2021

J. High Energ. Phys.

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“…However, this type of contribution may be relevant when considering surfaces with codimension-3 defects, such as caustics on a null surface, or when considering singular symmetry generators, such as superrotations[102,124].…”

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confidence: 99%

Anomalies in gravitational charge algebras of null boundaries and black hole entropy

Chandrasekaran

Speranza

2021

J. High Energ. Phys.

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175

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We revisit the covariant phase space formalism applied to gravitational theories with null boundaries, utilizing the most general boundary conditions consistent with a fixed null normal. To fix the ambiguity inherent in the Wald-Zoupas definition of quasilocal charges, we propose a new principle, based on holographic reasoning, that the flux be of Dirichlet form. This also produces an expression for the analog of the Brown-York stress tensor on the null surface. Defining the algebra of charges using the Barnich-Troessaert bracket for open subsystems, we give a general formula for the central — or more generally, abelian — extensions that appear in terms of the anomalous transformation of the boundary term in the gravitational action. This anomaly arises from having fixed a frame for the null normal, and we draw parallels between it and the holographic Weyl anomaly that occurs in AdS/CFT. As an application of this formalism, we analyze the near-horizon Virasoro symmetry considered by Haco, Hawking, Perry, and Strominger, and perform a systematic derivation of the fluxes and central charges. Applying the Cardy formula to the result yields an entropy that is twice the Bekenstein-Hawking entropy of the horizon. Motivated by the extended Hilbert space construction, we interpret this in terms of a pair of entangled CFTs associated with edge modes on either side of the bifurcation surface.

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“…See e.g [1][2][3][4][5][6][7]. and[8][9][10][11][12][13][14][15][16][17][18][19][20][21] for gauge-independent and gauge-dependent approaches, respectively.…”

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confidence: 99%

“…ε ab µ a µ b being positive. This fixes the relative signs and ambiguity in the comparison with the Bondi gauge 20. We recall that the heat current is transverse to the fluid velocity, therefore in two dimensions, thanks to Hodge duality and without loss of generality, we can describe the heat current in terms of a scalar χ.…”

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confidence: 99%

Fefferman--Graham and Bondi Gauges in the Fluid/Gravity Correspondence

Ciambelli¹,

Marteau²,

Petropoulos³

et al. 2020

Proceedings of Corfu Summer Institute 2019 "School and Workshops on Elementary Particle Physics and Gravity" — PoS(CORFU2019)

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In three-dimensional gravity, we discuss the relation between the Fefferman-Graham gauge, the Bondi gauge and the Eddington-Finkelstein type of gauge, often referred to as the derivative expansion, involved in the fluid/gravity correspondence. Starting with a negative cosmological constant, for each gauge, we derive the solution space and the residual gauge diffeomorphisms. We construct explicitly the diffeomorphisms that relate the various gauges, and establish the precise matching of their boundary data. We show that Bondi and Fefferman-Graham gauges are equivalent, while the fluid/gravity derivative expansion, originating from a partial gauge fixing, exhibits an extra unspecified function that encodes the boundary fluid velocity. The Bondi gauge turns out to describe a subspace of the derivative expansion's solution space, featuring a fluid in a specific hydrodynamic frame. We pursue our analysis with the Ricci-flat limit of the Bondi gauge and of the fluid/gravity derivative expansion. The relations between them persist in this limit, which is well-defined and non-trivial. Moreover, the flat limit of the derivative expansion maps to the ultra-relativistic limit on the boundary. This procedure allows to unravel the holographic properties of the Bondi gauge for vanishing cosmological constant, in terms of its boundary Carrollian dual fluid.

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Cosmic footballs from superrotations

Cited by 24 publications

References 44 publications

Super-Hawking radiation

Super-Hawking radiation

Anomalies in gravitational charge algebras of null boundaries and black hole entropy

Fefferman--Graham and Bondi Gauges in the Fluid/Gravity Correspondence

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