activity
20242026
collaborators

7 papers

gr-qc2026

Pole Skipping, Avoided Crossing, and Resonant Excitation in Kerr Quasinormal Modes near Algebraically Special Frequencies

Kei-ichiro Kubota, Hayato Motohashi

Kerr quasinormal modes near algebraically special frequencies exhibit anomalous behavior, including apparent bifurcation, disappearance, and a nonsmooth connection to the Schwarzsc…

gr-qc2026

Pole structure of the Kerr Green's function

Hayato Motohashi, Yuto Suichi

We investigate the pole structure of Kerr black-hole perturbations in the frequency domain, focusing on the building blocks of the Green's function for the radial Teukolsky equatio…

gr-qc2025

Resonance of black hole quasinormal modes in coupled systems

Takuya Takahashi, Hayato Motohashi, Kazufumi Takahashi

Black hole quasinormal modes (QNMs) can exhibit resonant excitations associated with avoided crossings in their complex frequency spectrum. Such resonance phenomena can serve as no…

gr-qc2025

Resonant Excitation of Quasinormal Modes of Black Holes

Hayato Motohashi

We elucidate that a distinctive resonant excitation between quasinormal modes (QNMs) of black holes emerges as a universal phenomenon at an avoided crossing near the exceptional po…

gr-qc2024

Spin wave optics for gravitational waves lensed by a Kerr black hole

Kei-ichiro Kubota, Shun Arai, Hayato Motohashi +1

Gravitational waves exhibit the unique signature of their spin-2 nature in processes of wave scattering, due to the interaction between spin and a background spacetime. Since the s…

gr-qc2024

Iterative extraction of overtones from black hole ringdown

Kazuto Takahashi, Hayato Motohashi

Extraction of multiple quasinormal modes from ringdown gravitational waves emitted from a binary black hole coalescence is a touchstone to test whether a remnant black hole is desc…