Probing bumblebee gravity with black hole X-ray data

Abstract

Abstract Bumblebee gravity is one of the simplest gravity theories with spontaneous Lorentz symmetry breaking. Since we know a rotating black hole solution in bumblebee gravity, we can potentially test this model with the available astrophysical observations of black holes. In this work, we construct a reflection model in bumblebee gravity and we use our model to analyze the reflection features of a NuSTAR spectrum of the Galactic black hole EXO 1846-031 in order to constrain the Lorentz-violating parameter $$\ell $$ ℓ . We find that the analysis of the reflection features in the spectrum of EXO 1846-031 cannot constrain the parameter $$\ell $$ ℓ because of a very strong degeneracy between the estimates of $$\ell $$ ℓ and of the black hole spin parameter $$a_*$$ a ∗ . Such a degeneracy may be broken by combining other observations.