Equatorial orbits and imaging of hairy cubic Galileon black holes

TL;DR

This paper studies the motion of particles around hairy black holes in cubic Galileon theory, revealing deviations from general relativity and producing accretion disk images to aid future observational constraints.

Contribution

It analyzes equatorial orbits and imaging of hairy black holes in cubic Galileon theory, highlighting deviations from GR and potential observational signatures.

Findings

Stable circular geodesics exist only below a critical coupling.

Deviations from general relativity depend on coupling and rotation.

Accretion disk images show distinctive features for these black holes.

Abstract

Null and timelike equatorial orbits are investigated in a family of hairy black holes in the cubic Galileon theory. These include rotating generalizations of static black hole metrics supporting a time-dependent scalar field. Depending on the coupling and rotation, the properties of the geodesics expectedly deviate from general relativity. In particular, it is found that stable circular geodesics only exist below a critical coupling, which is related to the existence of an outermost stable circular orbit. Focusing on the strong-field region, images of an accretion disk are also produced to highlight tendencies that would constrain the model given further accurate observations of supermassive black holes.