Magnetized accretion disks around Kerr black holes with scalar hair -- Nonconstant angular momentum disks

TL;DR

This paper develops new equilibrium models of magnetized thick disks around Kerr black holes with scalar hair, revealing how scalar hair influences disk morphology and potential observational signatures.

Contribution

Introduces a novel angular momentum distribution method for thick disks around hairy Kerr black holes, extending previous constant angular momentum models.

Findings

Scalar hair significantly alters disk morphology and properties.

Disks can exhibit two maxima in gravitational energy density.

Models serve as initial data for GRMHD simulations and shadow analysis.

Abstract

We present new equilibrium solutions of stationary models of magnetized thick disks (or tori) around Kerr black holes with synchronised scalar hair. The models reported here largely extend our previous results based on constant radial distributions of the specific angular momentum along the equatorial plane. We introduce a new way to prescribe the distribution of the disk's angular momentum based on a combination of two previous proposals and compute the angular momentum distribution outside the equatorial plane by resorting to the construction of von Zeipel cylinders. We find that the effect of the scalar hair on the black hole spacetime can yield significant differences in the disk morphology and properties compared to what is found if the spacetime is purely Kerr. Some of the tori built within the most extreme, background hairy black hole spacetime of our sample exhibit the appearance of two maxima in the gravitational energy density which impacts the radial profile distributions of the disk's thermodynamical quantities. The models reported in this paper can be used as initial data for numerical evolutions with GRMHD codes to study their stability properties. Moreover, they can be employed as illuminating sources to build shadows of Kerr black holes with scalar hair which might help further constrain the no-hair hypothesis as new observational data is collected.