Grey Galaxies’ as an endpoint of the Kerr-AdS superradiant instability

• Published in: The journal of high energy physics Vol. 2023; no. 11; pp. 24 - 106
• Main Authors: Kim, Seok, Kundu, Suman, Lee, Eunwoo, Lee, Jaeha, Minwalla, Shiraz, Patel, Chintan
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 06.11.2023; Springer Nature B.V; Springer Nature; SpringerOpen
• Subjects: AdS-CFT Correspondence; Angular velocity; Black Holes; Classical and Quantum Gravitation; Classical Theories of Gravity; Delta function; Elementary Particles; Galaxies; High energy physics; Physics; Physics and Astronomy; PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Regular Article - Theoretical Physics; Relativity Theory; String Theory; Supersymmetry; Tensors; Theoretical physics; Thermal Field Theory; Thermodynamics; Wave functions; Yang-Mills theory; AdS-CFT Correspondence; Classical Theories of Gravity; Black Holes; Thermal Field Theory
• ISSN: 1029-8479; 1029-8479
• DOI: 10.1007/JHEP11(2023)024

A bstract Kerr-AdS d +1 black holes for d ≥ 3 suffer from classical superradiant instabilities over a range of masses above extremality. We conjecture that these instabilities settle down into Grey Galaxies (GGs) — a new class of coarse-grained solutions to Einstein’s equations which we construct in d = 3. Grey Galaxies are made up of a black hole with critical angular velocity ω = 1 in the ‘centre’ of AdS, surrounded by a large flat disk of thermal bulk gas that revolves around the centre of AdS at the speed of light. The gas carries a finite fraction of the total energy, as its parametrically low energy density and large radius are inversely related. GGs exist at masses that extend all the way down to the unitarity bound. Their thermodynamics is that of a weakly interacting mix of Kerr-AdS black holes and the bulk gas. Their boundary stress tensor is the sum of a smooth ‘black hole’ contribution and a peaked gas contribution that is delta function localized around the equator of the boundary sphere in the large N limit. We also construct another class of solutions with the same charges; ‘Revolving Black Holes (RBHs)’. RBHs are macroscopically charged SO( d, 2) descendants of AdS-Kerr solutions, and consist of ω = 1 black holes revolving around the centre of AdS at a fixed radial location but in a quantum wave function in the angular directions. RBH solutions are marginally entropically subdominant to GG solutions and do not constitute the endpoint of the superradiant instability. Nonetheless, we argue that supersymmetric versions of these solutions have interesting implications for the spectrum of supersymmetric states in, e.g. N = 4 Yang-Mills theory.