Quasinormal modes of black holes: from astrophysics to string theory

TL;DR

This paper reviews recent advances in understanding black hole perturbations, focusing on quasinormal modes, their calculation methods, stability, and implications in astrophysics, string theory, and holography, including potential observational detection.

Contribution

It provides a comprehensive overview of recent progress in black hole perturbation theory, especially in higher dimensions and holographic contexts, highlighting new analytical and numerical techniques.

Findings

Decoupling of variables in perturbation equations

Development of numerical and analytical methods for QNMs

Discussion of observational prospects for detecting QNMs

Abstract

Perturbations of black holes, initially considered in the context of possible observations of astrophysical effects, have been studied for the past ten years in string theory, brane-world models and quantum gravity. Through the famous gauge/gravity duality, proper oscillations of perturbed black holes, called quasinormal modes (QNMs), allow for the description of the hydrodynamic regime in the dual finite temperature field theory at strong coupling, which can be used to predict the behavior of quark-gluon plasmas in the nonperturbative regime. On the other hand, the brane-world scenarios assume the existence of extra dimensions in nature, so that multidimensional black holes can be formed in a laboratory experiment. All this stimulated active research in the field of perturbations of higher-dimensional black holes and branes during recent years. In this review recent achievements on various aspects of black hole perturbations are discussed such as decoupling of variables in the perturbation equations, quasinormal modes (with special emphasis on various numerical and analytical methods of calculations), late-time tails, gravitational stability, AdS/CFT interpretation of quasinormal modes, and holographic superconductors. We also touch on state-of-the-art observational possibilities for detecting quasinormal modes of black holes.