Quasinormal modes of scalar, electromagnetic, and gravitational perturbations in slowly rotating Kalb-Ramond black holes

TL;DR

This paper studies how Lorentz-violating effects in slowly rotating Kalb-Ramond black holes influence quasinormal modes across scalar, electromagnetic, and gravitational perturbations, revealing potential observational signatures.

Contribution

It derives and computes the QNM spectrum in KR black holes considering Lorentz violation, showing its impact on oscillation and damping rates across different perturbations.

Findings

Lorentz violation increases QNM frequencies and damping rates.

Axial gravitational modes are most sensitive to Lorentz violation.

Theoretical bound on Lorentz-violating parameter: 5<0.5.

Abstract

We investigate quasinormal modes (QNMs) of scalar, electromagnetic, and axial gravitational perturbations in slowly rotating Kalb-Ramond (KR) black holes, where an antisymmetric tensor field induces spontaneous Lorentz symmetry breaking. Working consistently to first order in the dimensionless spin parameter, we derive the corresponding master equations and compute the QNM spectrum using both the continued-fraction and matrix methods, finding excellent agreement. Lorentz violation modifies the oscillation and damping rates in a unified manner across all perturbative sectors: the real part of the QNM frequency increases monotonically with the Lorentz-violating parameter $\ell$, while the imaginary part becomes more negative. Axial gravitational modes exhibit the strongest response, revealing an intrinsic theoretical bound $\ell< 0.5$, beyond which the spectrum approaches an extremal behavior. Our results highlight the potential of gravitational-wave spectroscopy to probe Lorentz-violating signatures in KR gravity.