Thin accretion disk signatures of scalarized black holes in Einstein-scalar-Gauss-Bonnet gravity

TL;DR

This study explores how thin accretion disks around scalarized black holes in Einstein-scalar-Gauss-Bonnet gravity differ observationally from those in general relativity, potentially allowing tests of this modified gravity theory.

Contribution

It provides a numerical analysis of accretion disk signatures around scalarized black holes, highlighting observable differences from standard black holes in general relativity.

Findings

Accretion disks are hotter and more luminous around scalarized black holes.

Differences in innermost stable circular orbits and energy efficiency.

Potential for observational tests of Einstein-scalar-Gauss-Bonnet gravity.

Abstract

Einstein-scalar-Gauss-Bonnet gravity has recently been known to exhibit spontaneous scalarization. In the presence of the Gauss-Bonnet term the no-hair theorem can be evaded and novel black hole solutions with non-trivial scalar fields have been found besides the general relativistic solutions. In this paper, we aim to investigate the possibility of observationally testing Einstein-scalar-Gauss-Bonnet gravity using thin accretion disk properties around such scalarized black holes. Using the Novikov-Thorne model, we numerically calculate the electromagnetic flux, temperature distribution, emission spectrum, innermost stable circular orbits and energy conversion efficiency of accretion disks around such black holes and compare the results with the standard general relativistic Schwarzschild solution. We find that the accretion disks around scalarized black holes are hotter and more luminous than in general relativity.