KerrNewman black holes with scalar hair
Abstract
We construct electrically charged Kerr black holes (BHs) with scalar hair. Firstly, we take an uncharged scalar field, interacting with the electromagnetic field only indirectly, via the background metric. The corresponding family of solutions, dubbed KerrNewman BHs with ungauged scalar hair, reduces to (a subfamily of) KerrNewman BHs in the limit of vanishing scalar hair and to uncharged rotating boson stars in the limit of vanishing horizon. It adds one extra parameter to the uncharged solutions: the total electric charge. This leading electromagnetic multipole moment is unaffected by the scalar hair and can be computed by using Gauss's law on any closed 2surface surrounding (a spatial section of) the event horizon. By contrast, the first subleading electromagnetic multipole  the magnetic dipole moment , gets suppressed by the scalar hair, such that the gyromagnetic ratio is always smaller than the KerrNewman value (g = 2). Secondly, we consider a gauged scalar field and obtain a family of KerrNewman BHs with gauged scalar hair. The electrically charged scalar field now stores a part of the total electric charge, which can only be computed by applying Gauss' law at spatial infinity and introduces a new solitonic limit  electrically charged rotating boson stars. In both cases, we analyze some physical properties of the solutions.
 Publication:

Physics Letters B
 Pub Date:
 October 2016
 DOI:
 10.1016/j.physletb.2016.08.032
 arXiv:
 arXiv:1608.00631
 Bibcode:
 2016PhLB..761..234D
 Keywords:

 General Relativity and Quantum Cosmology;
 High Energy Physics  Theory
 EPrint:
 11 pages, 4 figures