Black Hole Perturbations and Quasinormal Modes in Hybrid Metric-Palatini Gravity

TL;DR

This paper investigates the axial gravitational perturbations and quasinormal modes of black holes within hybrid metric-Palatini gravity, exploring their potential for testing gravity theories through gravitational wave observations.

Contribution

It derives the master equation for axial perturbations in HMPG and analyzes how QNM frequencies vary within observationally constrained parameters.

Findings

QNM frequencies are affected by HMPG parameters.

Constraints from post-Newtonian analysis limit the range of QNM variations.

Potential for black hole spectroscopy to test HMPG predictions.

Abstract

The rapid advancement of gravitational wave astronomy in recent years has paved the way for the burgeoning development of black hole spectroscopy, which enhances the possibility of testing black holes by their quasinormal modes (QNMs). In this paper, the axial gravitational perturbations and the QNM frequencies of black holes in the hybrid metric-Palatini gravity (HMPG) are investigated. The HMPG theory is characterized by a dynamical scalar degree of freedom and is able to explain the late-time accelerating expansion of the universe without introducing any \textit{ad hoc} screening mechanism to preserve the dynamics at the Solar System scale. We obtain the master equation governing the axial gravitational perturbations of the HMPG black holes and calculate the QNM frequencies. Moreover, in the scrutiny of the black holes and their QNMs, we take into account the constraints on the model parameters based on the post-Newtonian analysis, and show how the QNM frequencies of the HMPG black holes would be altered in the observationally consistent range of parameter space.