Graviscalar quasinormal modes and asymptotic tails of a thick brane

TL;DR

This paper studies the graviscalar quasinormal modes of a thick brane, revealing discrete decaying modes and long-lasting tails that could influence gravitational wave signals and encode brane properties.

Contribution

It introduces a detailed analysis of graviscalar QNMs in thick branes using multiple methods, highlighting their unique spectral features and tail behaviors.

Findings

Discrete graviscalar QNMs are identified.

Long-lived oscillatory tails are observed.

QNMs encode information about the brane structure.

Abstract

In this work, we investigate the graviscalar quasinormal modes (QNMs) and their asymptotic tail behavior of a thick brane. Considering the scalar perturbations of the thick brane metric, we obtain the main equations of graviscalar Kaluza-Klein modes. Based on these equations, the frequencies of the graviscalar QNMs of the thick brane are obtained by the Wentzel-Kramers-Brillouin, asymptotic iteration, and numerical evolution methods. The results show that the scalar fluctuation of the thick brane has a series of discrete QNMs, similar to the tensor perturbation of the brane. These modes appear as decaying massive scalar particles in four-dimensional spacetime. We also studied in detail the late time tails of these QNMs and found that some modes have slowly decaying oscillatory tails that may be new sources of the gravitational wave backgrounds. Obviously, the QNMs contain the information of the brane and are characteristic modes of the thick brane.