Work

Exact Cancellation of Horizon Modes in Kerr Ringdown

Year: 2026

Type: preprint

Abstract: Ringdown gravitational waves probe black hole spacetimes via quasinormal modes (QNMs). Recent studies have reported oscillatory features in QNM-filtered waveforms, and have led to conflicting interpretations as to whether they represent a near-horizon "direct wave". Reexamining a particle plunging into a Kerr black hole, we show that the saddle-point approximation underlying the proposed interpretation fails near the horizon. Our exact analysis reveals that every source-induced horizon-mode pole is canceled by an infinite tower of Matsubara zeros, independently of orbital and black-hole parameters. The first four stages of this sequential screening are also confirmed by time-domain numerical integration. Thus, within the near-horizon perturbative framework, source-induced horizon-mode signals do not survive at late times.

Source: arXiv (Cornell University)

DOI: 10.48550/arxiv.2609.07326

Authors: Kubota, Kei-ichiro, Manita, Yusuke, Motohashi, Hayato, Watarai, Daiki

Institutions: Institute for Cosmic Ray Research, The University of Tokyo, Perimeter Institute, Tokyo Metropolitan University, Research Center for the Early Universe

Language: English

Topic: Pulsars and Gravitational Waves Research

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: green

Funders: Government of Canada, Institut Périmètre de physique théorique, Ministry of Colleges and Universities, Japan Society for the Promotion of Science

Awards: Theoretical study toward multi-messenger observations of black holes, G6401233450

OpenAlex ID: W7212024393

Cites: 28

Cited by: 5

Related to: 10