Geodesic motion around hairy black holes

TL;DR

This paper investigates the motion of particles around new static black hole solutions with primary hairs, analyzing geodesics and observational constraints to understand their physical properties.

Contribution

It studies geodesic motion around recently discovered hairy black holes and constrains their parameters using observational data, linking them to Kerr black holes.

Findings

Effective potential and stable orbits characterized.

Constraints on primary hairs based on observational data.

Comparison with Kerr black hole properties.

Abstract

In a recent paper (Phys. Dark Univ. {\bf 31}, 100744 (2021)) it has been obtained new static black hole solutions with primary hairs by the Gravitational Decoupling. In this work we either study the geodesic motion of massive and massless particles around those solutions and restrict the values of the primary hairs by observational data. In particular, we obtain the effective potential, the innermost stable circular orbits, the marginally bounded orbit, and the periastron advance for time--like geodesics. In order to restrict the values taken by the primary hairs we explore their relationship with the rotation parameter of the Kerr black hole giving the same innermost stable circular orbit radius and give the numerical values for the supermassive black holes at Ark 564 and NGC 1365. The photon sphere and the impact parameter associated to null geodesics are also discussed.