How short can stationary charged scalar hair be?
Abstract
It is by now well established that charged rotating KerrNewman black holes can support boundstate chargedmatter configurations which are made of minimally coupled massivescalar fields. We here prove that the externally supported stationary charged scalar configurations cannot be arbitrarily compact. In particular, for linearizedchargedmassivescalar fields supported by charged rotating nearextremal KerrNewman black holes, we derive the remarkably compact lower bound (r_{field}r_{+})/(r_{+}r_{})>1 /s^{2} on the effective lengths of the external charged scalar "clouds" [here r_{field} is the radial peak location of the stationary scalar configuration, and {s ≡J /M^{2},r_{±}} are, respectively, the dimensionless angular momentum and the horizon radii of the central supporting KerrNewman black hole]. Remarkably, this lower bound is universal in the sense that it is independent of the physical parameters (proper mass, electric charge, and angular momentum) of the supported charged scalar fields.
 Publication:

Physical Review D
 Pub Date:
 January 2022
 DOI:
 10.1103/PhysRevD.105.024061
 arXiv:
 arXiv:2206.14819
 Bibcode:
 2022PhRvD.105b4061H
 Keywords:

 General Relativity and Quantum Cosmology;
 Astrophysics  High Energy Astrophysical Phenomena;
 High Energy Physics  Theory
 EPrint:
 8 pages