Ringing of rapidly rotating black holes in effective field theory
Authors:
Tom van der Steen,
Simon Maenaut,
Stef J. B. Husken,
Pedro G. S. Fernandes,
Maxim D. Jockwer,
Vitor Cardoso,
Thomas Hertog,
Tjonnie G. F. Li
Abstract:
Within the effective field theory approach to gravity, deviations from general relativity can be systematically described by higher-curvature operators. However, computing the resulting corrections to black hole quasinormal mode spectra remains challenging in the rapidly rotating regime, where perturbative expansions in the spin break down. We use recently constructed numerical rotating black hole…
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Within the effective field theory approach to gravity, deviations from general relativity can be systematically described by higher-curvature operators. However, computing the resulting corrections to black hole quasinormal mode spectra remains challenging in the rapidly rotating regime, where perturbative expansions in the spin break down. We use recently constructed numerical rotating black hole solutions to compute quasinormal mode frequency corrections at leading order in the effective field theory. Focusing on scalar perturbations, we evaluate cubic-curvature corrections, which constitute the leading modifications. We employ a pseudo-spectral collocation method to solve the resulting perturbation equations on these backgrounds, enabling accurate computation across a broad parameter range. We obtain frequency corrections for fundamental modes with $l\le5$ for all $m$, and the first overtone of $2 \le l \le 5$ modes for all $m$ for spins up to $a=0.99M$, with relative errors below $10^{-4}$. We observe that corrections to certain modes grow significantly as the spin approaches the near-extremal regime.
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Submitted 14 April, 2026; v1 submitted 13 April, 2026;
originally announced April 2026.
Quadratic gravity corrections to scalar QNMs of rapidly rotating black holes
Authors:
Stef J. B. Husken,
Tom van der Steen,
Simon Maenaut,
Kelvin Ka-Ho Lam,
Maxim D. Jockwer,
Adrian Ka-Wai Chung,
Thomas Hertog,
Tjonnie G. F. Li,
Nicolás Yunes
Abstract:
In an effective-field-theory framework for gravity, black-hole quasinormal mode spectra acquire corrections in quadratic-curvature, scalar-tensor extensions of general relativity. Previous calculations of such corrections were limited to moderate spins, since the corresponding background solutions relied on expansions in the spin parameter. Using recently constructed numerical black-hole solutions…
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In an effective-field-theory framework for gravity, black-hole quasinormal mode spectra acquire corrections in quadratic-curvature, scalar-tensor extensions of general relativity. Previous calculations of such corrections were limited to moderate spins, since the corresponding background solutions relied on expansions in the spin parameter. Using recently constructed numerical black-hole solutions valid for large spin, we compute the leading-order deviations from general relativity in the scalar quasinormal mode spectrum of rotating black holes in scalar Gauss-Bonnet and dynamical Chern-Simons gravity. We solve the resulting perturbation equations with pseudo-spectral collocation methods, allowing us to determine the quasinormal-mode corrections for dimensionless spins up to $a/M=0.99$, with accuracy better than $\lesssim 10^{-3}$ for the $l=m=0$ mode and $\lesssim 10^{-6}$ for higher multipoles. For spins $a/M>0.9$, the corrections to certain modes can increase by orders of magnitude.
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Submitted 14 April, 2026; v1 submitted 2 April, 2026;
originally announced April 2026.