Evolution of innermost stable circular orbit and light ring of a charged black hole induced by the scalarization

TL;DR

This study uses nonlinear simulations to analyze how the innermost stable circular orbit and light ring of a charged black hole evolve during dynamical scalarization, revealing increases in their radii.

Contribution

It introduces a dynamic analysis of ISCO and light ring evolution during black hole scalarization within Einstein-Maxwell-dilaton theory.

Findings

ISCO and light ring radii increase during scalarization

The evolution is tracked through time-dependent effective potentials

Results enhance understanding of black hole scalarization dynamics

Abstract

In this paper, we investigate the dynamical evolution of the innermost stable circular orbit (ISCO) and light ring of a charged black hole during dynamical scalarization. This is achieved through nonlinear simulations within the framework of the Einstein-Maxwell-dilaton theory. Using the time-dependent metric derived from these simulations, we compute the radial effective potentials for timelike and null geodesics as functions of time. Our results demonstrate how the ISCO and light ring evolve as a hairless charged black hole transitions to a scalarized state. We find that dynamical scalarization induces an increase in the areal radii of both the ISCO and light ring. These findings provide new insights into black hole scalarization, particularly regarding the temporal evolution of the ISCO and light ring in a dynamically evolving spacetime.