Quasinormal modes on Kerr spacetimes

Fuente: arXiv
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Auteurs principaux: Gajic, Dejan, Warnick, Claude M.
Format: Preprint
Publié: 2024
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author Gajic, Dejan
Warnick, Claude M.
author_facet Gajic, Dejan
Warnick, Claude M.
contents We introduce a rigorous framework for defining quasinormal modes on stationary, asymptotically flat spacetimes as isolated eigenvalues of the infinitesimal generator of time translations. We consider time functions corresponding to a foliation of asymptotically hyperboloidal hypersurfaces and restrict to suitable Hilbert spaces of functions. These functions have finite Sobolev regularity in bounded regions, but need to be Gevrey-regular at null infinity. This framework is developed in the context of sub-extremal Kerr spacetimes, but also gives uniform-in-$Λ$ resolvent estimates on Kerr--de Sitter spacetimes with a small cosmological constant $Λ$. As a corollary, we also construct the meromorphic continuation (in a sector of the complex plane) of the cut-off resolvent in Kerr that is associated to the standard Boyer--Lindquist time function. The framework introduced in this paper bridges different notions of quasinormal modes found in the literature. As further applications of our methods, we prove stability of quasinormal frequencies in a sector of the complex plane, with respect to suitably small perturbations and establish convergence properties for Kerr--de Sitter quasinormal frequencies when the cosmological constant approaches zero.
format Preprint
id arxiv_https___arxiv_org_abs_2407_04098
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Quasinormal modes on Kerr spacetimes
Gajic, Dejan
Warnick, Claude M.
General Relativity and Quantum Cosmology
Mathematical Physics
Analysis of PDEs
We introduce a rigorous framework for defining quasinormal modes on stationary, asymptotically flat spacetimes as isolated eigenvalues of the infinitesimal generator of time translations. We consider time functions corresponding to a foliation of asymptotically hyperboloidal hypersurfaces and restrict to suitable Hilbert spaces of functions. These functions have finite Sobolev regularity in bounded regions, but need to be Gevrey-regular at null infinity. This framework is developed in the context of sub-extremal Kerr spacetimes, but also gives uniform-in-$Λ$ resolvent estimates on Kerr--de Sitter spacetimes with a small cosmological constant $Λ$. As a corollary, we also construct the meromorphic continuation (in a sector of the complex plane) of the cut-off resolvent in Kerr that is associated to the standard Boyer--Lindquist time function. The framework introduced in this paper bridges different notions of quasinormal modes found in the literature. As further applications of our methods, we prove stability of quasinormal frequencies in a sector of the complex plane, with respect to suitably small perturbations and establish convergence properties for Kerr--de Sitter quasinormal frequencies when the cosmological constant approaches zero.
title Quasinormal modes on Kerr spacetimes
topic General Relativity and Quantum Cosmology
Mathematical Physics
Analysis of PDEs
url https://arxiv.org/abs/2407.04098