Recently, an exact rotating black hole solution in a parity-violating theory of gravity was obtained via a conformal transformation of the Kerr solution in general relativity, with parity-violating effects encoded in the conformal factor. We study the quasinormal modes (QNMs) of a test scalar field minimally coupled to gravity on this conformal Kerr background, treating the parity-violating effects perturbatively while allowing for arbitrary black hole spin, from the non-rotating case to the near-extremal regime. For low spin, we derive a perturbative formula for the QNM frequencies that includes the leading-order parity-violating correction. For high spin, particularly in the near-extremal regime, we find sizable deviations from the Kerr QNM frequencies. Our results point to a new avenue for probing parity-violating physics in the strong-gravity regime through black hole QNMs.
@article{arxiv.2603.03722,
title = {Scalar quasinormal modes of rotating black holes in parity-violating gravity},
author = {Hiroaki W. H. Tahara and Hayato Motohashi and Kazufumi Takahashi and Vicharit Yingcharoenrat},
journal= {arXiv preprint arXiv:2603.03722},
year = {2026}
}