Thin accretion disks around rotating black holes in $4D$ Einstein-Gauss-Bonnet gravity

TL;DR

This paper investigates how thin accretion disks around rotating black holes in 4D Einstein-Gauss-Bonnet gravity differ from Kerr black holes, showing that the Gauss-Bonnet coupling affects disk temperature and efficiency, which could help test this gravity theory.

Contribution

It analyzes accretion disk properties around 4D Einstein-Gauss-Bonnet black holes, revealing the influence of the Gauss-Bonnet coupling parameter on observable disk characteristics.

Findings

Positive coupling increases disk temperature and efficiency.

Negative coupling decreases disk temperature and efficiency.

Accretion disk properties can test Einstein-Gauss-Bonnet gravity.

Abstract

Recently, Kumar and Ghosh have derived Kerr-like rotating black hole solutions in the framework of four-dimensional Einstein-Gauss-Bonnet theory of gravity and investigated the black hole shadow. Using the steady-state Novikov-Thorne model, we study thin accretion disk processes for such rotating black holes including the energy flux, temperature distribution, emission spectrum, energy conversion efficiency as well as the radius of the innermost stable circular orbit. We also study the effects of the Gauss-Bonnet coupling parameter $\alpha$ on these quantities. The results are compared to slowly rotating relativistic Kerr black holes which show that for a positive Gauss-Bonnet coupling, thin accretion disks around rotating black holes in four-dimensional Einstein-Gauss-Bonnet gravity are hotter and more efficient than that for Kerr black holes with the same rotation parameter $a$, while for a negative coupling they are cooler and less efficient. Thus the accretion disk processes may be considered as tools for testing Einstein-Gauss-Bonnet gravity using astrophysical observations.