2025/10/01 by Rout, Abhishek, Altschul, Brett
#FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc)
paper · doi:10.48550/arxiv.2510.01106
We axial perturbations of Reissner-Nordström black holes within the framework of Chern-Simons modified gravity, a theory with includes parity violation. We derive the governing equations for the perturbations, focusing on the radial function R(r) and its behavior across distinct regions: near the singularity (r → 0), between the inner and outer Reissner-Nordström horizons (r-< r< r+), and in the asymptotic regime (r → ∞). Using a combination of analytical and numerical methods, we analyze the solutions for varying black hole charge-to-mass ratios (Q/M) and angular momentum parameters (l). Key findings include the suppression of perturbations by the electromagnetic field for higher Q/M; the emergence of radial resonance-like behavior for specific l values; and a high degree of symmetry for solutions in the extremal limit (Q/M ∼ 1), attributed to the AdS2 × S2 near-horizon geometry. The WKB approximation is employed to study high-l regimes, revealing quantized radial modes and singular behavior in the extremal limit. Additionally, we explore the role of boundary conditions and the Chern-Simons scalar field Θ, showing that consistency demands a constant field (and thus no actually observable Chern-Simons effects) in this perturbative framework. These results provide insights into the stability and dynamical properties of charged black holes under axial perturbations.