A Swampland-modified Hod bound for charged black holes with exotic matter

TL;DR

This paper investigates how quintessence and a cloud of strings affect charged black hole quasinormal modes, leading to a modified Hod bound that aligns with Swampland constraints and observable signatures.

Contribution

It introduces a Swampland-modified Hod bound for charged black holes considering exotic matter effects, linking black hole physics with quantum gravity constraints.

Findings

Both parameters influence black hole stability and oscillation frequencies.

The modified Hod bound is satisfied within a specific parameter region.

Black hole shadow and emission rates are affected by quintessence and string cloud parameters.

Abstract

In this paper, we study the quasinormal modes (QNMs) of a charged black hole in the presence of both quintessence and a cloud of strings using the Pade-averaged higher-order WKB approximation method. We investigate the effect of the quintessence parameter $\alpha$ and the cloud of strings parameter $\lambda$ on the stability as well as the oscillation frequency of perturbations. The validity of Hod's conjecture, which relates quasinormal frequencies to the black hole temperature, is tested throughout the physically allowed parameter space. Our results show that both the effective potential and the decay rate of perturbations depend on the values of $\alpha$ and $\lambda$, leading to either enhancement or suppression of the conditions required to satisfy Hod's bound. Furthermore, we discuss how these parameters modify the black hole shadow and the corresponding energy emission rate, revealing correlations with observable signatures. Finally, we establish a connection with the Swampland Distance Conjecture by expressing the Hawking temperature in terms of the scalar field excursion. Our analysis leads to a modified Hod bound and identifies a region of parameter space in which both the modified Hod bound and the Swampland constraints are simultaneously satisfied, ensuring consistency between black hole thermodynamics, observational properties, and quantum gravity constraints.