General parametrization of black holes: The only parameters that matter
Abstract
The general parametrization of a blackhole spacetime in arbitrary metric theories of gravity includes an infinite set of parameters. It is natural to suppose that essential astrophysically observable quantities, such as quasinormal modes, parameters of shadow, electromagnetic radiation and accreting matter in the vicinity of a black hole, must depend mostly on a few of these parameters. Starting from the parametrization for spherically symmetric configurations in the form of an infinite continued fraction, we suggest a compact representation of the asymptotically flat spherically symmetric and slowly rotating black holes in terms of only three and four parameters respectively. A subclass of arbitrarily rotating black holes belonging to the Carter family can also be parametrized by only four parameters. This approximate representation of a blackhole metric should allow one to describe physical observables in the region of strong gravity.
 Publication:

Physical Review D
 Pub Date:
 June 2020
 DOI:
 10.1103/PhysRevD.101.124004
 arXiv:
 arXiv:2001.06100
 Bibcode:
 2020PhRvD.101l4004K
 Keywords:

 General Relativity and Quantum Cosmology;
 Astrophysics  High Energy Astrophysical Phenomena;
 High Energy Physics  Theory
 EPrint:
 6 pages, 1 figure, new material on rotating black holes is added  the version accepted for publication in Physical Review D