Massive scalar field perturbation on Kerr black holes in dynamical Chern-Simons gravity

TL;DR

This paper investigates how massive scalar fields perturb Kerr black holes within dynamical Chern-Simons gravity, revealing conditions for tachyonic instability and how mass suppresses this instability through numerical simulations.

Contribution

It provides the first detailed numerical analysis of scalar perturbations on Kerr black holes in dynamical Chern-Simons gravity, highlighting the effects of mass and coupling on instability.

Findings

Tachyonic instability occurs for any nonzero spin and scalar mass if coupling exceeds a critical value.

Mass term suppresses or quenches the instability.

Quantitative relations between instability onset, coupling, mass, and spin are established.

Abstract

We study massive scalar field perturbation on Kerr black holes in dynamical Chern-Simons gravity by performing a $(2+1)$-dimensional simulation. Object pictures of the wave dynamics in time domain are obtained. The tachyonic instability is found to always occur for any nonzero black hole spin and any scalar field mass as long as the coupling constant exceeds a critical value. The presence of the mass term suppresses or even quenches the instability. The quantitative dependence of the onset of the tachyonic instability on the coupling constant, the scalar field mass and the black hole spin is given numerically.