H
Hirotada Okawa
Researcher at Waseda University
Publications - 69
Citations - 4140
Hirotada Okawa is an academic researcher from Waseda University. The author has contributed to research in topics: Neutrino & Numerical relativity. The author has an hindex of 25, co-authored 62 publications receiving 3506 citations. Previous affiliations of Hirotada Okawa include University of Lisbon & Kyoto University.
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Journal ArticleDOI
Testing general relativity with present and future astrophysical observations
Emanuele Berti,Emanuele Berti,Enrico Barausse,Vitor Cardoso,Vitor Cardoso,Leonardo Gualtieri,Paolo Pani,Paolo Pani,Ulrich Sperhake,Ulrich Sperhake,Ulrich Sperhake,Leo C. Stein,Leo C. Stein,Norbert Wex,Kent Yagi,Kent Yagi,Tessa Baker,C.P. Burgess,C.P. Burgess,Flávio S. Coelho,Daniela D. Doneva,Antonio De Felice,Pedro G. Ferreira,Paulo C. C. Freire,James Healy,Carlos A. R. Herdeiro,Michael Horbatsch,Burkhard Kleihaus,Antoine Klein,Kostas D. Kokkotas,Jutta Kunz,Pablo Laguna,Ryan N. Lang,Ryan N. Lang,Ryan N. Lang,Tjonnie G. F. Li,Tjonnie G. F. Li,Tyson Littenberg,Andrew Matas,S. Mirshekari,Hirotada Okawa,Eugen Radu,Richard O'Shaughnessy,Richard O'Shaughnessy,Bangalore Suryanarayana Sathyaprakash,Chris Van Den Broeck,Hans A. Winther,Helvi Witek,Mir Emad Aghili,Justin Alsing,Brett Bolen,Luca Bombelli,Sarah Caudill,Liang Chen,Juan Carlos Degollado,Ryuichi Fujita,Caixia Gao,Davide Gerosa,Saeed Kamali,Hector O. Silva,João G. Rosa,Laleh Sadeghian,Marco O. P. Sampaio,Hajime Sotani,Miguel Zilhão +64 more
TL;DR: In this article, a catalog of modified theories of gravity for which strong-field predictions have been computed and contrasted to Einstein's theory is presented, and the current understanding of the structure and dynamics of compact objects in these theories is summarized.
Journal ArticleDOI
Mass ejection from the merger of binary neutron stars
Kenta Hotokezaka,Kenta Kiuchi,Koutarou Kyutoku,Hirotada Okawa,Yuichiro Sekiguchi,Masaru Shibata,Keisuke Taniguchi +6 more
TL;DR: In this paper, numerical simulations for the merger of binary neutron stars are performed for a variety of equations of state (EOSs) and for a plausible range of the neutron star mass, focusing primarily on the properties of the material ejected from the system.
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Light rings as observational evidence for event horizons: Long-lived modes, ergoregions and nonlinear instabilities of ultracompact objects
TL;DR: In this article, the authors explore the mode structure of ultracompact stars, in particular constant-density stars and gravastars, and conjecture that the long-lived modes become unstable under fragmentation via a Dyson-Chandrasekhar-Fermi mechanism at the nonlinear level.
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Binary neutron star mergers: Dependence on the nuclear equation of state
TL;DR: In this article, a numerical simulation for binary neutron star mergers with 6 nuclear-theory-based equations of states (EOSs) described by piecewise polytropes is performed.
Journal ArticleDOI
Dynamical mass ejection from black hole-neutron star binaries
Koutarou Kyutoku,Kunihito Ioka,Kunihito Ioka,Hirotada Okawa,Hirotada Okawa,Masaru Shibata,Keisuke Taniguchi,Keisuke Taniguchi +7 more
TL;DR: In this paper, the authors investigate the properties of material ejected dynamically in the merger of black hole-neutron star binaries by numerical-relativity simulations and systematically study the dependence of ejecta properties on the mass ratio of the binary, spin of the black hole, and equation of state of the neutron-star matter.