activity
20242026
collaborators

6 papers

gr-qc2026

Limiting cases of second-order moments of relativistic stars and their universality

Koutarou Kyutoku

Extending the work presented in a workshop ``From Quarks to Neutron Stars: Insights from kHz gravitational waves'', we discuss some limiting cases of the moment of inertia, tidal d…

gr-qc2026

Finite signal-to-noise ratio bias in parameter estimation for damped oscillations: cautionary remark about catalog-level black-hole spectroscopy

Koutarou Kyutoku

We investigate biases in parameter estimation for damped oscillations motivated by applications to black-hole spectroscopy in gravitational-wave physics. Focusing on the simplest m…

astro-ph.HE2026

Higher-order statistics of the stochastic gravitational wave background from supermassive black hole binaries

Hinano Hisamatsu, Koutarou Kyutoku

Recent progress in gravitational wave observations has positioned Pulsar Timing Arrays as a key tool for detecting the stochastic gravitational wave background in the nanohertz ban…

gr-qc2025

Assessment of universal relations among second-order moments of relativistic stars via reformulated perturbation equations

Koutarou Kyutoku

We assess the universal relations among second-order moments of relativistic stars, namely the moment of inertia, tidal deformability, and spin-induced quadrupole moment, via refor…

astro-ph.HE2025

Signature of hadron-quark crossover in binary-neutron-star mergers

Yuki Fujimoto, Kenji Fukushima, Kenta Hotokezaka +1

We study observational signatures of the hadron-quark crossover in binary-neutron-star mergers by numerical-relativity simulations with various mass configurations. We employ two e…

astro-ph.HE2024

Jet from binary neutron star merger with prompt black hole formation

Kota Hayashi, Kenta Kiuchi, Koutarou Kyutoku +2

We performed the longest numerical-relativity neutrino-radiation magnetohydrodynamics simulation for a binary neutron star merger that extends to after the…