Kyoto University

An analytic model for a total process of gravitational collapse: From star to Schwarzschild black hole

Sinya Aoki, Jorge Ovalle

We present an exact analytical model describing a complete gravitational collapse of matter from horizonless initial conditions to black hole formation, tracing the full evolution…

gr-qc2026★ 2 cited

GW240925 and GW250207: Astrophysical Calibration of Gravitational-wave Detectors

The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration +1839

GW240925 and GW250207 are two loud gravitational-wave signals from binary black hole coalescences observed with network signal-to-noise ratios $\sim 32$ and $\sim 69$ , respectively…

Searches for Continuous Gravitational Waves from Supernova Remnants in the first part of the LIGO-Virgo-KAGRA Fourth Observing run

The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration +1764

We present results from directed searches for continuous gravitational waves from a sample of 15 nearby supernova remnants, likely hosting young neutron star candidates, using data…

Secular evolution of orbital parameters for general bound orbits in Kerr spacetime

Norichika Sago, Ryuichi Fujita, Soichiro Isoyama +1

We analytically derive the secular changes of the orbital parameters, i.e., energy, angular momentum, and Carter constant, for general bound orbits in Kerr spacetime, at leading or…

Narrowband searches for continuous gravitational waves from known pulsars in the first two parts of the fourth LIGO--Virgo--KAGRA observing run

The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration +1853

Rotating non-axisymmetric neutron stars (NSs) are promising sources for continuous gravitational waves (CWs). Such CWs can, if detected, inform us about the internal structure and…

The emergent Big Bang scenario

Justin C. Feng, Shinji Mukohyama, Jean-Philippe Uzan

This paper proposes a new avenue for understanding the cosmological singularity. The standard cosmological model contains a generic initial singularity usually referred to as the {…

Constraints on gravitational waves from the 2024 Vela pulsar glitch

The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration +1774

Among known neutron stars, the Vela pulsar is one of the best targets for gravitational-wave searches. It is also one of the most prolific in terms of glitches, sudden frequency ch…

Violation of the Leggett-Garg inequality in photon-graviton conversion

Kimihiro Nomura, Akira Taniguchi, Kazushige Ueda

The Leggett-Garg inequality (LGI) is a temporal analogue of Bell's inequality and provides a quantitative test of the nonclassicality of a system through its violation. We analytic…

Exceptional Lines and Excitation of (Nearly) Double-Pole Quasinormal Modes: A Semi-Analytic Study in the Nariai Black Hole

Nao Nakamoto, Naritaka Oshita

We show that quasinormal modes (QNMs) of a massive scalar field in Kerr-de Sitter and Myers-Perry black holes exhibit an exceptional line (EL), which is a continuous set of excepti…

gr-qc2025★ 2 cited

Is energy conserved in general relativity ?

Sinya Aoki

This short report is dedicated to the 40th anniversary of International Journal of Modern Physics A (IJMPA) and Modern Physics Letters A (MPLA). While the report is based on a seri…

gr-qc2025★ 1 cited

Quantum sensing of high-frequency gravitational waves with ion crystals

Asuka Ito, Ryuichiro Kitano, Wakutaka Nakano +1

A detection method for high-frequency gravitational waves using two-dimensional ion crystals is investigated. Gravitational waves can resonantly excite the drumhead modes of the io…

Spectral instability of parametrized black hole quasinormal modes in the high-overtone limit via the exact WKB analysis

Taiga Miyachi, Ryo Namba, Hidetoshi Omiya +1

We study the asymptotic behavior of parametrized black hole quasinormal modes (QNMs) in the high-overtone limit. To gain insights into their analytical structure, we apply the exac…

Search for planetary-mass ultra-compact binaries using data from the first part of the LIGO--Virgo--KAGRA fourth observing run

The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration +1765

We present a search for gravitational waves from inspiraling, planetary-mass ultra-compact binaries using data from the first part of the fourth observing run of LIGO, Virgo and KA…

gr-qc2025★ 1 cited

Exotic compact objects in Einstein-scalar-Maxwell theories

Antonio De Felice, Shinji Tsujikawa

In k-essence theories within general relativity, where the matter Lagrangian depends on a real scalar field $ϕ$ and its kinetic term $X$ , static and spherically symmetric compact o…

gr-qc2025★ 5 cited

Dynamical Tidal Response of Non-rotating Black Holes: Connecting the MST Formalism and Worldline EFT

Hajime Kobayashi, Shinji Mukohyama, Naritaka Oshita +2

The response of a black hole (BH) to tidal forces encodes key information about the underlying gravitational theory and affects the waveform of gravitational waves emitted during b…

Bayesian and Machine-Learning Analyses of Nonminimal $f (Q)$ Gravity and $H_{0}$ Tension

Simran Arora, Mridul Patel

In this study, the cosmological implications of nonminimally coupled $f (Q)$ gravity are examined within the metric-affine formalism, in which the nonmetricity scalar $Q$ couples di…

Directional Search for Persistent Gravitational Waves: Results from the First Part of LIGO-Virgo-KAGRA's Fourth Observing Run

The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration +1765

The angular distribution of gravitational-wave power from persistent sources may exhibit anisotropies arising from the large-scale structure of the Universe. This motivates directi…

gr-qc2025★ 100 cited

GW250114: testing Hawking's area law and the Kerr nature of black holes

The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration +1785

The gravitational-wave signal GW250114 was observed by the two LIGO detectors with a network matched-filter signal-to-noise ratio of 80. The signal was emitted by the coalescence o…