Axial Mode Stability and Quasinormal Modes of Charged Kiselev Black Holes in Rastall Gravity
Abstract
We investigate axial gravitoelectromagnetic perturbations of charged black holes surrounded by dust-like Kiselev-type anisotropic matter in Rastall gravity. We derive the axial matter compatibility condition and construct a compatible response by holding the covariant anisotropy-direction vector unperturbed. The resulting gravitational and electromagnetic perturbations obey two coupled Schrodinger-type master equations. An r-independent algebraic decoupling exists in the Reissner-Nordstrom and general-relativistic dust-like limits; additional radial structure obstructs it in generic charged Rastall backgrounds with nonzero surrounding matter. We prove axial mode stability under the adopted closure for every nonextremal background satisfying the stated exterior conditions, covering all physical axial multipoles. A matrix S-deformation excludes exponentially growing coupled modes for l >= 2, while the physical electromagnetic dipole has a positive effective potential. A Chebyshev pseudospectral calculation, validated against the Reissner-Nordstrom spectrum and spectral convergence, determines the fundamental frequencies. In the parameter ranges examined, increasing the Rastall coupling lowers both the oscillation frequency and the damping rate in the small-coupling region; in the large-coupling region, the oscillation frequency rises while the damping rate varies nonmonotonically. A larger charge generally raises the oscillation frequency, whereas stronger surrounding-matter contributions produce longer-lived modes.
Related
- Quasinormal modes of charged de Sitter black holes and strong cosmic censorship in conformal Killing gravity
- Dynamical Stability and Quasinormal Modes of Casimir Wormholes in dRGT Massive Gravity
- Remark About Action for Rastall Gravity
- Constraints on Rastall gravity from current observational data
- Axial gravitational quasinormal modes of magnetically charged black holes
BibTeX
@misc{wang2026axial,
title = {{Axial Mode Stability and Quasinormal Modes of Charged Kiselev Black Holes in Rastall Gravity}},
author = {Yan Wang and Yun-tao Gu and Wen-Di Guo},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2609.25565},
eprint = {2609.25565},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.25565},
}
RIS
TY - UNPB
TI - Axial Mode Stability and Quasinormal Modes of Charged Kiselev Black Holes in Rastall Gravity
AU - Yan Wang
AU - Yun-tao Gu
AU - Wen-Di Guo
PY - 2026
DA - 2026/10/18
PB - arXiv
DO - 10.48550/arxiv.2609.25565
UR - https://arxiv.org/abs/2609.25565
AB - We investigate axial gravitoelectromagnetic perturbations of charged black holes surrounded by dust-like Kiselev-type anisotropic matter in Rastall gravity. We derive the axial matter compatibility condition and construct a compatible response by holding the covariant anisotropy-direction vector unperturbed. The resulting gravitational and electromagnetic perturbations obey two coupled Schrodinger-type master equations. An r-independent algebraic decoupling exists in the Reissner-Nordstrom and general-relativistic dust-like limits; additional radial structure obstructs it in generic charged Rastall backgrounds with nonzero surrounding matter. We prove axial mode stability under the adopted closure for every nonextremal background satisfying the stated exterior conditions, covering all physical axial multipoles. A matrix S-deformation excludes exponentially growing coupled modes for l >= 2, while the physical electromagnetic dipole has a positive effective potential. A Chebyshev pseudospectral calculation, validated against the Reissner-Nordstrom spectrum and spectral convergence, determines the fundamental frequencies. In the parameter ranges examined, increasing the Rastall coupling lowers both the oscillation frequency and the damping rate in the small-coupling region; in the large-coupling region, the oscillation frequency rises while the damping rate varies nonmonotonically. A larger charge generally raises the oscillation frequency, whereas stronger surrounding-matter contributions produce longer-lived modes.
ER -