Optical Appearance and Ringdown of Black Holes in a Kalb Ramond Field Coupled to Perfect Fluid Dark Matter

TL;DR

This study explores how a Kalb-Ramond field coupled with perfect fluid dark matter influences black hole optics and ringdown signals, revealing parameter-dependent observational signatures and potential tests of Lorentz violation.

Contribution

It provides a detailed analysis of optical and quasinormal mode properties of black holes in this modified gravity-dark matter model, highlighting new effects on observables.

Findings

Black hole optical appearance is affected by model parameters.

Quasinormal modes depend on Lorentz-violating and dark matter parameters.

Good agreement between quasinormal modes and null geodesic properties in the eikonal limit.

Abstract

This paper investigates the optical and dynamical properties of a static spherically symmetric black hole in the presence of a Kalb--Ramond (KR) field coupled to perfect fluid dark matter (PFDM). We analyze the effects of the Lorentz-violating parameter $\alpha$ and the dark matter parameter $\lambda$ on photon trajectories and their observational signatures in the strong-gravity regime. Furthermore, we study the quasinormal mode spectrum under scalar, electromagnetic, and gravitational perturbations, examining how the model parameters influence the characteristic oscillation frequencies and damping rates. In particular, the interplay between the effective potential structure and perturbative dynamics is clarified, and it is found that, within the validity of the eikonal approximation, the quasinormal modes of the black hole considered here exhibit good agreement with the properties of null geodesics. Our results show that the model parameters significantly affect both the optical appearance of the black hole and the dynamical features of the ringdown phase, providing potential observational constraints on Lorentz-violating effects and dark matter environments in strong-field regimes.