Published Papers - Taniguchi Keisuke

Equilibriums of extremely magnetized compact stars with force-free magnetotunnels

Kōji Uryū, Shijun Yoshida, Eric Gourgoulhon, Charalampos Markakis, Kotaro Fujisawa, Antonios Tsokaros, Keisuke Taniguchi, Mina Zamani

Physical Review D ( Physical Review D )  107 ( 10 ) 103016-1 - 103016-14   2023.05 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Reducing orbital eccentricity in initial data of black hole-neutron star binaries in the puncture framework

Kyutoku Koutarou, Kawaguchi Kyohei, Kiuchi Kenta, Shibata Masaru, Taniguchi Keisuke

PHYSICAL REVIEW D ( Physical Review D )  103 ( 2 ) 023002-1 - 023002-15   2021.01 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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New code for equilibriums and quasiequilibrium initial data of compact objects. IV. Rotating relativistic stars with mixed poloidal and toroidal magnetic fields

Koji Uryu, Shijun Yoshida, Eric Gourgoulhon, Charalampos Markakis, Kotaro Fujisawa, Antonios Tsokaros, Keisuke Taniguchi, Yoshiharu Eriguchi

Physical Review D ( Physical Review D )  100 ( 12 ) 123019-1 - 123019-34   2019.12 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Revisiting the Lower Bound on Tidal Deformability Derived by AT 2017gfo

Kenta Kiuchi, Koutarou Kyutoku, Masaru Shibata, Keisuke Taniguchi

Astrophysical Journal Letters ( Astrophysical Journal Letters )  876 ( 2 ) L31-1 - L31-6   2019.05 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Frequency-domain gravitational waveform models for inspiraling binary neutron stars

Kyohei Kawaguchi, Kenta Kiuchi, Koutarou Kyutoku, Yuichiro Sekiguchi, Masaru Shibata, Keisuke Taniguchi

Physical Review D ( Physical Review D )  97 ( 4 ) 044044-1 - 044044-22   2018.02 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Neutrino transport in black hole-neutron star binaries: Neutrino emission and dynamical mass ejection

Koutarou Kyutoku, Kenta Kiuchi, Yuichiro Sekiguchi, Masaru Shibata, Keisuke Taniguchi

Physical Review D ( Physical Review D )  97 ( 2 ) 023009-1 - 023009-17   2018.01 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Modeling differential rotations of compact stars in equilibriums

Koji Uryū, Antonios Tsokaros, Luca Baiotti, Filippo Galeazzi, Keisuke Taniguchi, Shin'ichirou Yoshida

Physical Review D ( Physical Review D )  96 ( 10 ) 103011-1 - 103011-8   2017.11 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Sub-radian-accuracy gravitational waveforms of coalescing binary neutron stars in numerical relativity

Kenta Kiuchi, Kyohei Kawaguchi, Koutarou Kyutoku, Yuichiro Sekiguchi, Masaru Shibata, Keisuke Taniguchi

Physical Review D ( Physical Review D )  96 ( 8 ) 084060-1 - 084060-13   2017.10 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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The status of DECIGO

Shuichi Sato, Seiji Kawamura, Masaki Ando, Takashi Nakamura, Kimio Tsubono, Akito Araya, Ikkoh Funaki, Kunihito Ioka, Nobuyuki Kanda, Shigenori Moriwaki, Mitsuru Musha, Kazuhiro Nakazawa, Kenji Numata, Shin-ichiro Sakai, Naoki Seto, Takeshi Takashima, Takahiro Tanaka, Kazuhiro Agatsuma, Koh-suke Aoyanagi, Koji Arai, Hideki Asada, Yoichi Aso, Takeshi Chiba, Toshikazu Ebisuzaki, Yumiko Ejiri, Motohiro Enoki, Yoshiharu Eriguchi, Masa-Katsu Fujimoto, Ryuichi Fujita, Mitsuhiro Fukushima, Toshifumi Futamase, Katsuhiko Ganzu, Tomohiro Harada, Tatsuaki Hashimoto, Kazuhiro Hayama, Wataru Hikida, Yoshiaki Himemoto, Hisashi Hirabayashi, Takashi Hiramatsu, Feng-Lei Hong, Hideyuki Horisawa, Mizuhiko Hosokawa, Kiyotomo Ichiki, Takeshi Ikegami, Kaiki T. Inoue, Koji Ishidoshiro, Hideki Ishihara, Takehiko Ishikawa, Hideharu Ishizaki, Hiroyuki Ito, Yousuke Itoh, Nobuki Kawashima, Fumiko Kawazoe, Naoko Kishimoto, Kenta Kiuchi, Shiho Kobayashi, Kazunori Kohri, Hiroyuki Koizumi, Yasufumi Kojima, Keiko Kokeyama, Wataru Kokuyama, Kei Kotake, Yoshihide Kozai, Hideaki Kudoh, Hiroo Kunimori, Hitoshi Kuninaka, Kazuaki Kuroda, Kei-ichi Maeda, Hideo Matsuhara, Yasushi Mino, Osamu Miyakawa, Shinji Miyoki, Mutsuko Y. Morimoto, Tomoko Morioka, Toshiyuki Morisawa, Shinji Mukohyama, Shigeo Nagano, Isao Naito, Kouji Nakamura, Hiroyuki Nakano, Kenichi Nakao, Shinichi Nakasuka, Yoshinori Nakayama, Erina Nishida, Kazutaka Nishiyama, Atsushi Nishizawa, Yoshito Niwa, Taiga Noumi, Yoshiyuki Obuchi, Masatake Ohashi, Naoko Ohishi, Masashi Ohkawa, Norio Okada, Kouji Onozato, Kenichi Oohara, Norichika Sago, Motoyuki Saijo, Masaaki Sakagami, Shihori Sakata, Misao Sasaki, Takashi Sato, Masaru Shibata, Hisaaki Shinkai, Kentaro Somiya, Hajime Sotani, Naoshi Sugiyama, Yudai Suwa, Rieko Suzuki, Hideyuki Tagoshi, Fuminobu Takahashi, Kakeru Takahashi, Keitaro Takahashi, Ryutaro Takahashi, Ryuichi Takahashi, Tadayuki Takahashi, Hirotaka Takahashi, Takamori Akiteru, Tadashi Takano, Keisuke Taniguchi, Atsushi Taruya, Hiroyuki Tashiro, Yasuo Torii, Morio Toyoshima, Shinji Tsujikawa, Yoshiki Tsunesada, Akitoshi Ueda, Ken-ichi Ueda, Masayoshi Utashima, Yaka Wakabayashi, Hiroshi Yamakawa, Kazuhiro Yamamoto, Toshitaka Yamazaki, Jun’ichi Yokoyama, Chul-Moon Yoo, Shijun Yoshida, Taizoh Yoshino

Journal of Physics: Conference Series ( IOP Publishing )  840   012010 - 012010   2017.05 [ Peer Review Accepted ]

Type of publication: Research paper (international conference proceedings)

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Do triaxial supramassive compact stars exist?

Koji Uryu, Antonios Tsokaros, Luca Baiotti, Filippo Galeazzi, Noriyuki Sugiyama, Keisuke Taniguchi, Shin'ichirou Yoshida

Physical Review D ( Physical Review D )  94 ( 10 ) 101302-1 - 101302-6   2016.11 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Dynamical mass ejection from the merger of asymmetric binary neutron stars: Radiation-hydrodynamics study in general relativity

Yuichiro Sekiguchi, Kenta Kiuchi, Koutarou Kyutoku, Masaru Shibata, Keisuke Taniguchi

Physical Review D ( Physical Review D )  93 ( 12 ) 124046-1 - 124046-13   2016.06 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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New code for equilibriums and quasiequilibrium initial data of compact objects. III. Axisymmetric and triaxial rotating stars

Koji Uryu, Antonios Tsokaros, Filippo Galeazzi, Hideya Hotta, Misa Sugimura, Keisuke Taniguchi, Shin'ichirou Yoshida

Physical Review D ( Physical Review D )  93 ( 4 ) 044056-1 - 044056-18   2016.02 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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High resolution magnetohydrodynamic simulation of black hole-neutron star merger: Mass ejection and short gamma ray bursts

Kenta Kiuchi, Yuichiro Sekiguchi, Koutarou Kyutoku, Masaru Shibata, Keisuke Taniguchi, Tomohide Wada

Physical Review D - Particles, Fields, Gravitation and Cosmology ( Physical Review D - Particles, Fields, Gravitation and Cosmology )  92 ( 6 ) 064034-1 - 064034-8   2015.09 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Dynamical mass ejection from black hole-neutron star binaries

Koutarou Kyutoku, Kunihito Ioka, Hirotada Okawa, Masaru Shibata, Keisuke Taniguchi

Physical Review D - Particles, Fields, Gravitation and Cosmology ( Physical Review D - Particles, Fields, Gravitation and Cosmology )  92 ( 4 ) 044028-1 - 044028-37   2015.08 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Black hole-neutron star binary merger: Dependence on black hole spin orientation and equation of state

Kyohei Kawaguchi, Koutarou Kyutoku, Hiroyuki Nakano, Hirotada Okawa, Masaru Shibata, Keisuke Taniguchi

Physical Review D - Particles, Fields, Gravitation and Cosmology ( Physical Review D - Particles, Fields, Gravitation and Cosmology )  92 ( 2 ) 024014-1 - 024014-25   2015.07 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Quasiequilibrium sequences of binary neutron stars undergoing dynamical scalarization

Keisuke Taniguchi, Masaru Shibata, Alessandra Buonanno

Physical Review D   91   024033   2015.01 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Reducing orbital eccentricity in initial data of binary neutron stars

Kyutoku Koutarou, Shibata Masaru, Taniguchi Keisuke

PHYSICAL REVIEW D ( AMER PHYSICAL SOC )  90 ( 6 )   2014.09 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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We develop a method to compute low-eccentricity initial data of binary neutron stars required to perform realistic simulations in numerical relativity. The orbital eccentricity is controlled by adjusting the orbital angular velocity of a binary and incorporating an approaching relative velocity of the neutron stars. These modifications improve the solution primarily through the hydrostatic equilibrium equation for the binary initial data. The orbital angular velocity and approaching velocity of initial data are updated iteratively by performing time evolutions over similar to 3 orbits. We find that the eccentricity can be reduced by an order of magnitude compared to standard quasicircular initial data, specifically from similar to 0.01 to less than or similar to 0.001, by three successive iterations for equal-mass binaries leaving similar to 10 orbits before the merger.

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Coalescence of binary neutron stars in a scalar-tensor theory of gravity

Shibata Masaru, Taniguchi Keisuke, Okawa Hirotada, Buonanno Alessandra

PHYSICAL REVIEW D ( AMER PHYSICAL SOC )  89 ( 8 )   2014.04 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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We carry out numerical-relativity simulations of coalescing binary neutron stars in a scalar-tensor theory that admits spontaneous scalarization. We model neutron stars with realistic equations of state. We choose the free parameters of the theory taking into account the constraints imposed by the latest observations of neutron-star-white-dwarf binaries with pulsar timing. We show that even within those severe constraints, scalarization can still affect the evolution of the binary neutron stars, not only during the late inspiral but also during the merger stage. We also confirm that even when both neutron stars have quite small scalar charge at large separations, they can be strongly scalarized dynamically during the final stages of the inspiral. In particular, we identify the binary parameters for which scalarization occurs either during the late inspiral or only after the onset of the merger when a remnant, supramassive, or hypermassive neutron star is formed. We also discuss how those results can impact the extraction of physical information on gravitational waves once they are detected.

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Matter effects on binary neutron star waveforms

Read Jocelyn S., Baiotti Luca, Creighton Jolien D. E., Friedman John L., Giacomazzo Bruno, Kyutoku Koutarou, Markakis Charalampos, Rezzolla Luciano, Shibata Masaru, Taniguchi Keisuke

PHYSICAL REVIEW D ( AMER PHYSICAL SOC )  88 ( 4 )   2013.08 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Using an extended set of equations of state and a multiple-group multiple-code collaborative effort to generate waveforms, we improve numerical-relativity-based data-analysis estimates of the measurability of matter effects in neutron-star binaries. We vary two parameters of a parametrized piecewise-polytropic equation of state (EOS) to analyze the measurability of EOS properties, via a parameter Lambda that characterizes the quadrupole deformability of an isolated neutron star. We find that, to within the accuracy of the simulations, the departure of the waveform from point-particle (or spinless double black-hole binary) inspiral increases monotonically with Lambda and changes in the EOS that did not change Lambda are not measurable. We estimate with two methods the minimal and expected measurability of Lambda in second- and third-generation gravitational-wave detectors. The first estimate using numerical waveforms alone shows that two EOSs which vary in radius by 1.3 km are distinguishable in mergers at 100 Mpc. The second estimate relies on the construction of hybrid waveforms by matching to post-Newtonian inspiral and estimates that the same EOSs are distinguishable in mergers at 300 Mpc. We calculate systematic errors arising from numerical uncertainties and hybrid construction, and we estimate the frequency at which such effects would interfere with template-based searches.

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Remnant massive neutron stars of binary neutron star mergers: Evolution process and gravitational waveform

Hotokezaka Kenta, Kiuchi Kenta, Kyutoku Koutarou, Muranushi Takayuki, Sekiguchi Yu-ichiro, Shibata Masaru, Taniguchi Keisuke

PHYSICAL REVIEW D ( AMER PHYSICAL SOC )  88 ( 4 )   2013.08 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Massive (hypermassive and supramassive) neutron stars are likely to be often formed after the merger of binary neutron stars. We explore the evolution process of the remnant massive neutron stars and gravitational waves emitted by them, based on numerical-relativity simulations for binary neutron star mergers employing a variety of equations of state and choosing a plausible range of the neutron star mass of binaries. We show that the lifetime of remnant hypermassive neutron stars depends strongly on the total binary mass and also on the equations of state. Gravitational waves emitted by the remnant massive neutron stars universally have a quasiperiodic nature of an approximately constant frequency although the frequency varies with time. We also show that the frequency and time-variation feature of gravitational waves depend strongly on the equations of state. We derive a fitting formula for the quasiperiodic gravitational waveforms, which may be used for the data analysis of a gravitational-wave signal.

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Mass ejection from the merger of binary neutron stars

Hotokezaka Kenta, Kiuchi Kenta, Kyutoku Koutarou, Okawa Hirotada, Sekiguchi Yu-ichiro, Shibata Masaru, Taniguchi Keisuke

PHYSICAL REVIEW D ( AMER PHYSICAL SOC )  87 ( 2 )   2013.01 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Numerical-relativity 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. We find that a fraction of the material is ejected as a mildly relativistic and mildly anisotropic outflow with the typical and maximum velocities similar to 0.15-0.25c and similar to 0.5-0.8c (where c is the speed of light), respectively, and that the total ejected rest mass is in a wide range 10(-4)-10(-2)M(circle dot), which depends strongly on the EOS, the total mass, and the mass ratio. The total kinetic energy ejected is also in a wide range between 10(49) and 10(51) ergs. The numerical results suggest that for a binary of canonical total mass 2.7M(circle dot), the outflow could generate an electromagnetic signal observable by the planned telescopes through the production of heavy-element unstable nuclei via the r-process [6,20,21] or through the formation of blast waves during the interaction with the interstellar matter [7], if the EOS and mass of the binary are favorable ones. DOI: 10.1103/PhysRevD.87.024001

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Gravitational waves from black hole-neutron star binaries: Classification of waveforms (vol 79, 044030, 2009)

Shibata Masaru, Kyutoku Koutarou, Yamamoto Tetsuro, Taniguchi Keisuke

PHYSICAL REVIEW D ( AMER PHYSICAL SOC )  85 ( 12 )   2012.06 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Gravitational waves from spinning black hole-neutron star binaries: dependence on black hole spins and on neutron star equations of state

Kyutoku Koutarou, Okawa Hirotada, Shibata Masaru, Taniguchi Keisuke

PHYSICAL REVIEW D ( AMER PHYSICAL SOC )  84 ( 6 )   2011.09 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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We study the merger of black hole-neutron star binaries with a variety of black hole spins aligned or antialigned with the orbital angular momentum, and with the mass ratio in the range M-BH/M-NS = 2-5, where M-BH and M-NS are the mass of the black hole and neutron star, respectively. We model neutron-star matter by systematically parametrized piecewise polytropic equations of state. The initial condition is computed in the puncture framework adopting an isolated horizon framework to estimate the black hole spin and assuming an irrotational velocity field for the fluid inside the neutron star. Dynamical simulations are performed in full general relativity by an adaptive-mesh refinement code, SACRA. The treatment of hydrodynamic equations and estimation of the disk mass are improved. We find that the neutron star is tidally disrupted irrespective of the mass ratio when the black hole has a moderately large prograde spin, whereas only binaries with low mass ratios, M-BH/M-NS less than or similar to 3, or small compactnesses of the neutron stars bring the tidal disruption when the black hole spin is zero or retrograde. The mass of the remnant disk is accordingly large as greater than or similar to 0.1M(circle dot), which is required by central engines of short gamma-ray bursts, if the black hole spin is prograde. Information of the tidal disruption is reflected in a clear relation between the compactness of the neutron star and an appropriately defined "cutoff frequency" in the gravitational-wave spectrum, above which the spectrum damps exponentially. We find that the tidal disruption of the neutron star and excitation of the quasinormal mode of the remnant black hole occur in a compatible manner in high mass-ratio binaries with the prograde black hole spin. The correlation between the compactness and the cutoff frequency still holds for such cases. It is also suggested by extrapolation that the merger of an extremely spinning black hole and an irrotational neutron star binary does not lead to the formation of an overspinning black hole.

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New exact solutions of magnetic ellipsoidal figures of equilibrium

Kawamura Takumu, Taniguchi Keisuke, Yoshida Shin'ichirou, Eriguchi Yoshiharu

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY ( OXFORD UNIV PRESS )  416 ( 1 ) L75 - L79   2011.09 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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In this Letter we report brand new analytic stationary solutions of constant density stars with magnetic field and self-gravity. These solutions include prolate configurations even for purely poloidal magnetic fields as well as oblate configurations. These new analytic solutions are expressed in very simple forms and can be considered as generalized configurations of uniformly rotating constant density spheroids, i.e. Maclaurin spheroids, and of constant density ellipsoids with constant vorticity, i.e. Dedekind ellipsoids. As the axisymmetric Maclaurin spheroids and the triaxial Dedekind ellipsoids have been widely used for the estimation of the effect of rotations and/or internal motions on the self-gravitating bodies, our new analytic solutions may be used widely to estimate the effect of the magnetic fields semi-quantitatively in various contexts hereafter.

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The Japanese space gravitational wave antenna: DECIGO

Kawamura Seiji, Ando Masaki, Seto Naoki, Sato Shuichi, Nakamura Takashi, Tsubono Kimio, Kanda Nobuyuki, Tanaka Takahiro, Yokoyama Jun'ichi, Funaki Ikkoh, Numata Kenji, Ioka Kunihito, Takashima Takeshi, Agatsuma Kazuhiro, Akutsu Tomotada, Aoyanagi Koh-suke, Arai Koji, Araya Akito, Asada Hideki, Aso Yoichi, Chen Dan, Chiba Takeshi, Ebisuzaki Toshikazu, Ejiri Yumiko, Enoki Motohiro, Eriguchi Yoshiharu, Fujimoto Masa-Katsu, Fujita Ryuichi, Fukushima Mitsuhiro, Futamase Toshifumi, Harada Tomohiro, Hashimoto Tatsuaki, Hayama Kazuhiro, Hikida Wataru, Himemoto Yoshiaki, Hirabayashi Hisashi, Hiramatsu Takashi, Hong Feng-Lei, Horisawa Hideyuki, Hosokawa Mizuhiko, Ichiki Kiyotomo, Ikegami Takeshi, Inoue Kaiki T., Ishidoshiro Koji, Ishihara Hideki, Ishikawa Takehiko, Ishizaki Hideharu, Ito Hiroyuki, Itoh Yousuke, Izumi Kiwamu, Kawano Isao, Kawashima Nobuki, Kawazoe Fumiko, Kishimoto Naoko, Kiuchi Kenta, Kobayashi Shiho, Kohri Kazunori, Koizumi Hiroyuki, Kojima Yasufumi, Kokeyama Keiko, Kokuyama Wataru, Kotake Kei, Kozai Yoshihide, Kunimori Hiroo, Kuninaka Hitoshi, Kuroda Kazuaki, Kuroyanagi Sachiko, Maeda Kei-ichi, Matsuhara Hideo, Matsumoto Nobuyuki, Michimura Yuta, Miyakawa Osamu, Miyamoto Umpei, Miyoki Shinji, Morimoto Mutsuko Y., Morisawa Toshiyuki, Moriwaki Shigenori, Mukohyama Shinji, Musha Mitsuru, Nagano Shigeo, Naito Isao, Nakamura Kouji, Nakano Hiroyuki, Nakao Kenichi, Nakasuka Shinichi, Nakayama Yoshinori, Nakazawa Kazuhiro, Nishida Erina, Nishiyama Kazutaka, Nishizawa Atsushi, Niwa Yoshito, Noumi Taiga, Obuchi Yoshiyuki, Ohashi Masatake, Ohishi Naoko, Ohkawa Masashi, Okada Kenshi, Okada Norio, Oohara Kenichi, Sago Norichika, Saijo Motoyuki, Saito Ryo, Sakagami Masaaki, Sakai Shin-ichiro, Sakata Shihori, Sasaki Misao, Sato Takashi, Shibata Masaru, Shinkai Hisaaki, Shoda Ayaka, Somiya Kentaro, Sotani Hajime, Sugiyama Naoshi, Suwa Yudai, Suzuki Rieko, Tagoshi Hideyuki, Takahashi Fuminobu, Takahashi Kakeru, Takahashi Keitaro, Takahashi Ryutaro, Takahashi Ryuichi, Takahashi Tadayuki, Takahashi Hirotaka, Akiteru Takamori, Takano Tadashi, Tanaka Nobuyuki, Taniguchi Keisuke, Taruya Atsushi, Tashiro Hiroyuki, Torii Yasuo, Toyoshima Morio, Tsujikawa Shinji, Tsunesada Yoshiki, Ueda Akitoshi, Ueda Ken-ichi, Utashima Masayoshi, Wakabayashi Yaka, Yagi Kent, Yamakawa Hiroshi, Yamamoto Kazuhiro, Yamazaki Toshitaka, Yoo Chul-Moon, Yoshida Shijun, Yoshino Taizoh, Sun Ke-Xun

CLASSICAL AND QUANTUM GRAVITY ( IOP PUBLISHING LTD )  28 ( 9 )   2011.05 [ Peer Review Accepted ]

Type of publication: Research paper (international conference proceedings)

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The objectives of the DECi-hertz Interferometer Gravitational Wave Observatory (DECIGO) are to open a new window of observation for gravitational wave astronomy and to obtain insight into significant areas of science, such as verifying and characterizing inflation, determining the thermal history of the universe, characterizing dark energy, describing the formation mechanism of supermassive black holes in the center of galaxies, testing alternative theories of gravity, seeking black hole dark matter, understanding the physics of neutron stars and searching for planets around double neutron stars. DECIGO consists of four clusters of spacecraft in heliocentric orbits; each cluster employs three drag-free spacecraft, 1000 km apart from each other, whose relative displacements are measured by three pairs of differential Fabry-Perot Michelson interferometers. Two milestone missions, DECIGO pathfinder and Pre-DECIGO, will be launched to demonstrate required technologies and possibly to detect gravitational waves.

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Gravitational waves from nonspinning black hole-neutron star binaries: Dependence on equations of state

Kyutoku Koutarou, Shibata Masaru, Taniguchi Keisuke

PHYSICAL REVIEW D ( AMER PHYSICAL SOC )  82 ( 4 )   2010.08 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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We report results of a numerical-relativity simulation for the merger of a black hole-neutron star binary with a variety of equations of state (EOSs) modeled by piecewise polytropes. We focus, in particular, on the dependence of the gravitational waveform at the merger stage on the EOSs. The initial conditions are computed in the moving-puncture framework, assuming that the black hole is nonspinning and the neutron star has an irrotational velocity field. For a small mass ratio of the binaries (e.g., M-BH/M-NS = 2, where M-BH and M-NS are the masses of the black hole and neutron star, respectively), the neutron star is tidally disrupted before it is swallowed by the black hole irrespective of the EOS. Especially for less-compact neutron stars, the tidal disruption occurs at a more distant orbit. The tidal disruption is reflected in a cutoff frequency of the gravitational-wave spectrum, above which the spectrum amplitude exponentially decreases. A clear relation is found between the cutoff frequency of the gravitational-wave spectrum and the compactness of the neutron star. This relation also depends weakly on the stiffness of the EOS in the core region of the neutron star, suggesting that not only the compactness but also the EOS at high density is reflected in gravitational waveforms. The mass of the disk formed after the merger shows a similar correlation with the EOS, whereas the spin of the remnant black hole depends primarily on the mass ratio of the binary, and only weakly on the EOS. Properties of the remnant disks are also analyzed.

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BINARY NEUTRON STARS IN QUASI-EQUILIBRIUM

Taniguchi Keisuke, Shibata Masaru

ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES ( IOP PUBLISHING LTD )  188 ( 1 ) 187 - 208   2010.05 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Quasi-equilibrium sequences of binary neutron stars are constructed for a variety of equations of state in general relativity. Einstein's constraint equations in the Isenberg-Wilson-Mathews approximation are solved together with the relativistic equations of hydrostationary equilibrium under the assumption of irrotational flow. We focus on unequal-mass sequences as well as equal-mass sequences, and compare those results. We investigate the behavior of the binding energy and total angular momentum along a quasi-equilibrium sequence, the endpoint of sequences, and the orbital angular velocity as a function of time, changing the mass ratio, the total mass of the binary system, and the equation of state of a neutron star. It is found that the orbital angular velocity at the mass-shedding limit can be determined by an empirical formula derived from an analytic estimation. We also provide tables for 160 sequences, which will be useful as a guideline of numerical simulations for the inspiral and merger performed in the near future.

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DECIGO and DECIGO pathfinder

Ando Masaki, Kawamura Seiji, Seto Naoki, Sato Shuichi, Nakamura Takashi, Tsubono Kimio, Takashima Takeshi, Funaki Ikkoh, Numata Kenji, Kanda Nobuyuki, Tanaka Takahiro, Ioka Kunihito, Agatsuma Kazuhiro, Aoyanagi Koh-suke, Arai Koji, Araya Akito, Asada Hideki, Aso Yoichi, Chiba Takeshi, Ebisuzaki Toshikazu, Ejiri Yumiko, Enoki Motohiro, Eriguchi Yoshiharu, Fujimoto Masa-Katsu, Fujita Ryuichi, Fukushima Mitsuhiro, Futamase Toshifumi, Harada Tomohiro, Hashimoto Tatsuaki, Hayama Kazuhiro, Hikida Wataru, Himemoto Yoshiaki, Hirabayashi Hisashi, Hiramatsu Takashi, Hong Feng-Lei, Horisawa Hideyuki, Hosokawa Mizuhiko, Ichiki Kiyotomo, Ikegami Takeshi, Inoue Kaiki T., Ishidoshiro Koji, Ishihara Hideki, Ishikawa Takehiko, Ishizaki Hideharu, Ito Hiroyuki, Itoh Yousuke, Izumi Kiwamu, Kawano Isao, Kawashima Nobuki, Kawazoe Fumiko, Kishimoto Naoko, Kiuchi Kenta, Kobayashi Shiho, Kohri Kazunori, Koizumi Hiroyuki, Kojima Yasufumi, Kokeyama Keiko, Kokuyama Wataru, Kotake Kei, Kozai Yoshihide, Kunimori Hiroo, Kuninaka Hitoshi, Kuroda Kazuaki, Maeda Kei-ichi, Matsuhara Hideo, Mino Yasushi, Miyakawa Osamu, Miyamoto Umpei, Miyoki Shinji, Morimoto Mutsuko Y., Morisawa Toshiyuki, Moriwaki Shigenori, Mukohyama Shinji, Musha Mitsuru, Nagano Shigeo, Naito Isao, Nakamura Kouji, Nakamura Masahiro, Nakano Hiroyuki, Nakao Kenichi, Nakasuka Shinichi, Nakayama Yoshinori, Nakazawa Kazuhiro, Nishida Erina, Nishiyama Kazutaka, Nishizawa Atsushi, Niwa Yoshito, Noumi Taiga, Obuchi Yoshiyuki, Ohashi Masatake, Ohishi Naoko, Ohkawa Masashi, Okada Kenshi, Okada Norio, Oohara Kenichi, Sago Norichika, Saijo Motoyuki, Saito Ryo, Sakagami Masaaki, Sakai Shin-ichiro, Sakata Shihori, Sasaki Misao, Sato Takashi, Shibata Masaru, Shinkai Hisaaki, Somiya Kentaro, Sotani Hajime, Sugiyama Naoshi, Suwa Yudai, Suzuki Rieko, Tagoshi Hideyuki, Takahashi Fuminobu, Takahashi Kakeru, Takahashi Keitaro, Takahashi Ryutaro, Takahashi Ryuichi, Takahashi Tadayuki, Takahashi Hirotaka, Akiteru Takamori, Takano Tadashi, Taniguchi Keisuke, Taruya Atsushi, Tashiro Hiroyuki, Torii Yasuo, Toyoshima Morio, Tsujikawa Shinji, Tsunesada Yoshiki, Ueda Akitoshi, Ueda Ken-ichi, Utashima Masayoshi, Wakabayashi Yaka, Yagi Kent, Yamakawa Hiroshi, Yamamoto Kazuhiro, Yamazaki Toshitaka, Yokoyama Jun'ichi, Yoo Chul-Moon, Yoshida Shijun, Yoshino Taizoh, Sun Ken-Xun

CLASSICAL AND QUANTUM GRAVITY ( IOP PUBLISHING LTD )  27 ( 8 )   2010.04 [ Peer Review Accepted ]

Type of publication: Research paper (international conference proceedings)

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A space gravitational-wave antenna, DECIGO (DECI-hertz interferometer Gravitational wave Observatory), will provide fruitful insights into the universe, particularly on the formation mechanism of supermassive black holes, dark energy and the inflation of the universe. In the current pre-conceptual design, DECIGO will be comprising four interferometer units; each interferometer unit will be formed by three drag-free spacecraft with 1000 km separation. Since DECIGO will be an extremely challenging mission with high-precision formation flight with long baseline, it is important to increase the technical feasibility before its planned launch in 2027. Thus, we are planning to launch two milestone missions. DECIGO pathfinder (DPF) is the first milestone mission, and key components for DPF are being tested on ground and in orbit. In this paper, we review the conceptual design and current status of DECIGO and DPF.

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Exploring Binary-Neutron-Star-Merger Scenario of Short-Gamma-Ray Bursts by Gravitational-Wave Observation

Kiuchi Kenta, Sekiguchi Yuichiro, Shibata Masaru, Taniguchi Keisuke

PHYSICAL REVIEW LETTERS ( AMER PHYSICAL SOC )  104 ( 14 ) 141101   2010.04 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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We elucidate the feature of gravitational waves (GWs) from a binary-neutron-star merger collapsing to a black hole by general relativistic simulation. We show that GW spectrum imprints the coalescence dynamics, formation process of disk, equation of state for neutron stars, total masses, and mass ratio. A formation mechanism of the central engine of short-gamma-ray bursts, which are likely to be composed of a black hole and surrounding disk, therefore could be constrained by GW observation.

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Long-term general relativistic simulation of binary neutron stars collapsing to a black hole

Kiuchi Kenta, Sekiguchi Yuichiro, Shibata Masaru, Taniguchi Keisuke

PHYSICAL REVIEW D ( AMER PHYSICAL SOC )  80 ( 6 )   2009.09 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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General relativistic simulations for the merger of binary neutron stars are performed as an extension of a previous work [M. Shibata and K. Taniguchi, Phys. Rev. D 73, 064027 (2006).]. We prepare binary neutron stars with a large initial orbital separation and employ the moving-puncture formulation, which enables one to follow merger and ringdown phases for a long time, even after black hole formation. For modeling inspiraling neutron stars, which should be composed of cold neutron stars, the Akmal-Pandharipande-Ravenhall (APR) equation of state (EOS) is adopted. After the onset of merger, the hybrid-type EOS is used; i.e., the cold and thermal parts are given by the APR and Gamma-law EOSs, respectively. Three equal-mass binaries, each with mass 1:4M(circle dot), 1.45M(circle dot), and 1.5M(circle dot), and two unequal-mass binaries with mass, 1.3 vs 1.6M(circle dot) and 1.35 vs 1.65M(circle dot), are prepared. We focus primarily on the black hole formation case, and explore mass and spin of the black hole, mass of disks which surround the black hole, and gravitational waves emitted during the black hole formation. We find that (i) the black hole is promptly formed if total mass of the system initially satisfies m(0) >= 2.9M(circle dot); (ii) for the systems of m(0) = 2.9-3.0M(circle dot) and of mass ratio approximate to 0.8, the mass of disks which surround the formed black hole is 0.006-0.02M(circle dot); (iii) the spin of the formed black hole is 0.78 +/- 0.02 when a black hole is formed after the merger in the dynamical time scale. This value depends weakly on the total mass and mass ratio, and is about 0.1 larger than that of a black hole formed from nonspinning binary black holes; (iv) for the black hole formation case, Fourier spectrum shape of gravitational waves emitted in the merger and ringdown phases has a universal qualitative feature irrespective of the total mass and mass ratio, but quantitatively, the spectrum reflects the parameters of the binary neutron stars.

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Quasiequilibrium states of black hole-neutron star binaries in the moving-puncture framework

Kyutoku Koutarou, Shibata Masaru, Taniguchi Keisuke

PHYSICAL REVIEW D ( AMER PHYSICAL SOC )  79 ( 12 )   2009.06 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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General relativistic quasiequilibrium states of black hole-neutron star binaries are computed in the moving-puncture framework. We propose three conditions for determining the quasiequilibrium states and compare the numerical results with those obtained in the excision framework. We find that the results obtained in the moving-puncture framework agree with those in the excision framework and with those in the third post-Newtonian approximation for the cases that (i) the mass ratio of the binary is close to unity irrespective of the orbital separation, and (ii) the orbital separation is large enough (m(0)Omega less than or similar to 0.02, where m(0) and Omega are the total mass and the orbital angular velocity, respectively) irrespective of the mass ratio. For m(0)Omega greater than or similar to 0.03, both of the results in the moving-puncture and excision frameworks deviate, more or less, from those in the third post-Newtonian approximation. Thus the numerical results do not provide a quasicircular state, rather they seem to have a non-negligible eccentricity of order 0.01-0.1. We show by numerical simulation that a method in the moving-puncture framework can provide approximately quasicircular states in which the eccentricity is by a factor of similar to 2 smaller than those in quasiequilibrium given by other approaches.

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DECIGO pathfinder

Ando Masaki, Kawamura Seiji, Sato Shuichi, Nakamura Takashi, Tsubono Kimio, Araya Akito, Funaki Ikkoh, Ioka Kunihito, Kanda Nobuyuki, Moriwaki Shigenori, Musha Mitsuru, Nakazawa Kazuhiro, Numata Kenji, Sakai Shin-ichiro, Seto Naoki, Takashima Takeshi, Tanaka Takahiro, Agatsuma Kazuhiro, Aoyanagi Koh-suke, Arai Koji, Asada Hideki, Aso Yoichi, Chiba Takeshi, Ebisuzaki Toshikazu, Ejiri Yumiko, Enoki Motohiro, Eriguchi Yoshiharu, Fujimoto Masa-Katsu, Fujita Ryuichi, Fukushima Mitsuhiro, Futamase Toshifumi, Ganzu Katsuhiko, Harada Tomohiro, Hashimoto Tatsuaki, Hayama Kazuhiro, Hikida Wataru, Himemoto Yoshiaki, Hirabayashi Hisashi, Hiramatsu Takashi, Hong Feng-Lei, Horisawa Hideyuki, Hosokawa Mizuhiko, Ichiki Kiyotomo, Ikegami Takeshi, Inoue Kaiki T., Ishidoshiro Koji, Ishihara Hideki, Ishikawa Takehiko, Ishizaki Hideharu, Ito Hiroyuki, Itoh Yousuke, Kawashima Nobuki, Kawazoe Fumiko, Kishimoto Naoko, Kiuchi Kenta, Kobayashi Shiho, Kohri Kazunori, Koizumi Hiroyuki, Kojima Yasufumi, Kokeyama Keiko, Kokuyama Wataru, Kotake Kei, Kozai Yoshihide, Kudoh Hideaki, Kunimori Hiroo, Kuninaka Hitoshi, Kuroda Kazuaki, Maeda Kei-ichi, Matsuhara Hideo, Mino Yasushi, Miyakawa Osamu, Miyoki Shinji, Morimoto Mutsuko Y., Morioka Tomoko, Morisawa Toshiyuki, Mukohyama Shinji, Nagano Shigeo, Naito Isao, Nakamura Kouji, Nakano Hiroyuki, Nakao Kenichi, Nakasuka Shinichi, Nakayama Yoshinori, Nishida Erina, Nishiyama Kazutaka, Nishizawa Atsushi, Niwa Yoshito, Noumi Taiga, Obuchi Yoshiyuki, Ohashi Masatake, Ohishi Naoko, Ohkawa Masashi, Okada Norio, Onozato Kouji, Oohara Kenichi, Sago Norichika, Saijo Motoyuki, Sakagami Masaaki, Sakata Shihori, Sasaki Misao, Sato Takashi, Shibata Masaru, Shinkai Hisaaki, Somiya Kentaro, Sotani Hajime, Sugiyama Naoshi, Suwa Yudai, Suzuki Rieko, Tagoshi Hideyuki, Takahashi Fuminobu, Takahashi Kakeru, Takahashi Keitaro, Takahashi Ryutaro, Takahashi Ryuichi, Takahashi Tadayuki, Takahashi Hirotaka, Akiteru Takamori, Takano Tadashi, Taniguchi Keisuke, Taruya Atsushi, Tashiro Hiroyuki, Torii Yasuo, Toyoshima Morio, Tsujikawa Shinji, Tsunesada Yoshiki, Ueda Akitoshi, Ueda Ken-ichi, Utashima Masayoshi, Wakabayashi Yaka, Yamakawa Hiroshi, Yamamoto Kazuhiro, Yamazaki Toshitaka, Yokoyama Jun'ichi, Yoo Chul-Moon, Yoshida Shijun, Yoshino Taizoh

CLASSICAL AND QUANTUM GRAVITY ( IOP PUBLISHING LTD )  26 ( 9 )   2009.05 [ Peer Review Accepted ]

Type of publication: Research paper (international conference proceedings)

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DECIGO pathfinder (DPF) is a milestone satellite mission for DECIGO (DECi-hertz Interferometer Gravitational wave Observatory), which is a future space gravitational wave antenna. DECIGO is expected to provide fruitful insights into the universe, particularly about dark energy, the formation mechanism of supermassive black holes and the inflation of the universe. Since DECIGO will be an extremely challenging mission, which will be formed by three drag-free spacecraft with 1000 km separation, it is important to increase the technical feasibility of DECIGO before its planned launch in 2024. Thus, we are planning to launch two milestone missions: DPF and pre-DECIGO. In this paper, we review the conceptual design and current status of the first milestone mission, DPF.

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Equilibrium initial data for moving puncture simulations: the stationary 1+log slicing

Baumgarte T. W., Etienne Z. B., Liu Y. T., Matera K., Murchadha N. O., Shapiro S. L., Taniguchi K.

CLASSICAL AND QUANTUM GRAVITY ( IOP Publishing )  26 ( 8 ) 085007 - 085007   2009.04 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Gravitational waves from black hole-neutron star binaries: Classification of waveforms

Shibata Masaru, Kyutoku Koutarou, Yamamoto Tetsuro, Taniguchi Keisuke

PHYSICAL REVIEW D ( AMER PHYSICAL SOC )  79 ( 4 )   2009.02 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Using our new numerical-relativity code SACRA, long-term simulations for inspiral and merger of black hole (BH)-neutron star (NS) binaries are performed, focusing particularly on gravitational waveforms. As the initial conditions, BH-NS binaries in a quasiequilibrium state are prepared in a modified version of the moving-puncture approach. The BH is modeled by a nonspinning moving puncture and, for the NS, a polytropic equation of state with Gamma=2 and the irrotational velocity field are employed. The mass ratio of the BH to the NS, Q=M-BH/M-NS, is chosen in the range between 1.5 and 5. The compactness of the NS, defined by C=GM(NS)/c(2)R(NS), is chosen to be between 0.145 and 0.178. For a large value of Q for which the NS is not tidally disrupted and is simply swallowed by the BH, gravitational waves are characterized by inspiral, merger and ringdown waveforms. In this case, the waveforms are qualitatively the same as that from BH-BH binaries. For a sufficiently small value of Q less than or similar to 2, the NS may be tidally disrupted before it is swallowed by the BH. In this case, the amplitude of the merger and ringdown waveforms is very low, and thus, gravitational waves are characterized by the inspiral waveform and subsequent quick damping. The difference in the merger and ringdown waveforms is clearly reflected in the spectrum shape and in the "cutoff" frequency above which the spectrum amplitude steeply decreases. When a NS is not tidally disrupted (e.g., for Q=5), kick velocity, induced by asymmetric gravitational-wave emission, agrees approximately with that derived for the merger of BH-BH binaries, whereas for the case when the tidal disruption occurs, the kick velocity is significantly suppressed.

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Simulating coalescing compact binaries by a new code (SACRA)

Yamamoto Tetsuro, Shibata Masaru, Taniguchi Keisuke

PHYSICAL REVIEW D ( AMER PHYSICAL SOC )  78 ( 6 )   2008.09 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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We report our new code, named SACRA (SimulAtor for Compact objects in Relativistic Astrophysics) for numerical relativity simulations in which an adaptive mesh refinement algorithm is implemented. In this code, the Einstein equations are solved in the Baumgarte-Shapiro-Shibata-Nakamura formalism with a fourth-order finite differencing, and the hydrodynamic equations are solved by a third-order high-resolution central scheme. The fourth-order Runge-Kutta scheme is adopted for integration in time. To test the code, simulations for coalescence of black hole-black hole, neutron star-neutron star (NS-NS), and black hole-neutron star (BH-NS) binaries are performed, and also, properties of BHs formed after the merger and gravitational waveforms are compared among those three cases. For the simulations of black hole-black hole binaries, we adopt the same initial conditions as those by Buonanno et al. [1] and compare numerical results. We find reasonable agreement except for a slight disagreement possibly associated with the difference in choice of gauge conditions and numerical schemes. For an NS-NS binary, we performed simulations employing both SACRA and Shibata's previous code, and find reasonable agreement between two numerical results for the final outcome and qualitative property of gravitational waveforms. We also find that the convergence is relatively slow for numerical results of NS-NS binaries, and again realize that long-term numerical simulations with several resolutions and grid settings are required for validating the results. For a BH-NS binary, we compare numerical results with our previous ones, and find that gravitational waveforms and properties of the BH formed after the merger agree well with those of our previous ones, although the disk mass formed after the merger is less than 0.1% of the total rest mass, which disagrees with the previous result. We also report numerical results of a long-term simulation (with similar to 4 orbits) for a BH-NS binary for the first time. All these numerical results show behavior of convergence, and extrapolated numerical results for time spent in the inspiral phase agree with post-Newtonian predictions in a reasonable accuracy. These facts validate the results by SACRA.

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General relativistic simulations of magnetized binary neutron star mergers

Liu Yuk Tung, Shapiro Stuart L., Etienne Zachariah B., Taniguchi Keisuke

PHYSICAL REVIEW D ( AMER PHYSICAL SOC )  78 ( 2 )   2008.07 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Binary neutron stars (NSNS) are expected to be among the leading sources of gravitational waves observable by ground-based laser interferometers and may be the progenitors of short-hard gamma-ray bursts. We present a series of general relativistic NSNS coalescence simulations both for unmagnetized and magnetized stars. We adopt quasiequilibrium initial data for circular, irrotational binaries constructed in the conformal thin-sandwich (CTS) framework. We adopt the BSSN formulation for evolving the metric and a high-resolution shock-capturing scheme to handle the magnetohydrodynamics. Our simulations of unmagnetized binaries agree with the results of Shibata, Taniguchi and Uryu [M. Shibata, K. Taniguchi, and K. Uryu, Phys. Rev. D 68, 084020 (2003).]. In cases in which the mergers result in a prompt collapse to a black hole, we are able to use puncture gauge conditions to extend the evolution and determine the mass of the material that forms a disk. We find that the disk mass is less than 2% of the total mass in all cases studied. We then add a small poloidal magnetic field to the initial configurations and study the subsequent evolution. For cases in which the remnant is a hypermassive neutron star, we see measurable differences in both the amplitude and phase of the gravitational waveforms following the merger. For cases in which the remnant is a black hole surrounded by a disk, the disk mass and the gravitational waveforms are about the same as the unmagnetized cases. Magnetic fields substantially affect the long-term, secular evolution of a hypermassive neutron star (driving "delayed collapse") and an accretion disk around a nascent black hole.

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Fully general relativistic simulations of black hole-neutron star mergers

Etienne Zachariah B., Faber Joshua A., Liu Yuk Tung, Shapiro Stuart L., Taniguchi Keisuke, Baumgarte Thomas W.

PHYSICAL REVIEW D ( AMER PHYSICAL SOC )  77 ( 8 )   2008.04 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Black hole-neutron star (BHNS) binaries are expected to be among the leading sources of gravitational waves observable by ground-based detectors, and may be the progenitors of short-hard gamma-ray bursts (SGRBs) as well. We discuss our new fully general relativistic calculations of merging BHNS binaries, which use high-accuracy, low-eccentricity, conformal thin-sandwich configurations as initial data. Our evolutions are performed using the moving puncture method and include a fully relativistic, high-resolution shock-capturing hydrodynamics treatment. Focusing on systems in which the neutron star is irrotational and the black hole is nonspinning with a 31 mass ratio, we investigate the inspiral, merger, and disk formation in the system. We find that the vast majority of material is promptly accreted and no more than 3% of the neutron star's rest mass is ejected into a tenuous, gravitationally bound disk. We find similar results for mass ratios of 21 and 11, even when we reduce the neutron stars (NS) compaction in the 21 mass ratio case. These ambient disks reach temperatures suitable for triggering SGRBs, but their masses may be too small to produce the required total energy output. We measure gravitational waveforms and compute the effective strain in frequency space, finding measurable differences between our waveforms and those produced by binary black hole mergers within the advanced LIGO band. These differences appear at frequencies corresponding to the emission that occurs when the NS is tidally disrupted and accreted by the black hole. The resulting information about the radius of the neutron star may be used to constrain the neutron star equation of state.

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Merger of black hole and neutron star in general relativity: Tidal disruption, torus mass, and gravitational waves

Shibata Masaru, Taniguchi Keisuke

PHYSICAL REVIEW D ( AMER PHYSICAL SOC )  77 ( 8 )   2008.04 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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We study the properties of the merger of black hole-neutron star (BH-NS) binaries in fully general relativistic simulation, focusing on the case that the NS is tidally disrupted. We prepare BH-NS binaries in a quasicircular orbit as the initial condition in which the BH is modeled by a nonspinning moving puncture. For modeling the NS, we adopt the Gamma-law equation of state with Gamma=2 and the irrotational velocity field. We change the BH mass in the range M-BH approximate to 3.3M-4.6M, while the rest mass of the NS is fixed to be M-* = 1.4M (i.e., the NS mass M-NS approximate to 1.3M). The radius of the corresponding spherical NS is set in the range R-NS approximate to 12-15 km (i.e., the compactness GM(NS)/R(NS)c(2) approximate to 0.13-0.16). We find for all the chosen initial conditions that the NS is tidally disrupted near the innermost stable circular orbit. The numerical results indicate that, for the model of R-NS = 12 km, more than similar to 95% of the rest mass is quickly swallowed by the BH and the resultant torus mass surrounding the BH is less than similar to 0.05M. For the model of R-NS approximate to 14.7 km, by contrast, the torus mass is similar to 0.15M for the BH mass approximate to 4M. The thermal energy of the material in the torus increases due to the shock heating that occurs in the collision between the spiral arms, resulting in the temperature 10(10)-10(11) K. Our results indicate that the merger between a low-mass BH and its companion NS may form a central engine of short gamma-ray bursts of the total energy of order 10(49) ergs if the compactness of the NS is fairly small, less than or similar to 0.145. However, for the canonical values M-NS = 1.35M and R-NS = 12 km, the merger results in small torus mass, and hence it can be a candidate only for the low-energy, short gamma-ray bursts of total energy of order 10(48) ergs. We also present gravitational waveforms during the inspiral, tidal disruption of the NS, and subsequent evolution of the disrupted material. We find that the amplitude of gravitational waves quickly decreases after the onset of tidal disruption. Although the quasinormal mode is excited, its gravitational wave amplitude is much smaller than that of the late inspiral phase. This is reflected in the fact that the spectrum amplitude sharply falls above a cutoff frequency which is determined by the tidal disruption process. We also find that the cutoff frequency is 1.25-1.4 times larger than the frequency predicted by the study for the sequence of the quasicircular orbits, and this factor of the deviation depends on the compactness of the NS.

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Relativistic black hole-neutron star binaries in quasiequilibrium: Effects of the black hole excision boundary condition

Taniguchi Keisuke, Baumgarte Thomas W., Faber Joshua A., Shapiro Stuart L.

PHYSICAL REVIEW D ( AMER PHYSICAL SOC )  77 ( 4 )   2008.02 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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We construct new models of black hole-neutron star binaries in quasiequilibrium circular orbits by solving Einstein's constraint equations in the conformal thin-sandwich decomposition together with the relativistic equations of hydrostationary equilibrium. We adopt maximal slicing, assume spatial conformal flatness, and impose equilibrium boundary conditions on an excision surface (i.e., the apparent horizon) to model the black hole. In our previous treatment we adopted a "leading-order" approximation for a parameter related to the black hole spin in these boundary conditions to construct approximately nonspinning black holes. Here we improve on the models by computing the black hole's quasilocal spin angular momentum and setting it to zero. As before, we adopt a polytropic equation of state with adiabatic index Gamma=2 and assume the neutron star to be irrotational. In addition to recomputing several sequences for comparison with our earlier results, we study a wider range of neutron star masses and binary mass ratios. To locate the innermost stable circular orbit we search for turning points along both the binding energy and total angular momentum curves for these sequences. Unlike for our previous approximate boundary condition, these two minima now coincide. We also identify the formation of cusps on the neutron star surface, indicating the onset of tidal disruption. Comparing these two critical binary separations for different mass ratios and neutron star compactions we distinguish those regions that will lead to a tidal disruption of the neutron star from those that will result in the plunge into the black hole of a neutron star more or less intact, albeit distorted by tidal forces.

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DECIGO Pathfinder

Masaki Ando, Seiji Kawamura, Takashi Nakamura, Kimio Tsubono, Takahiro Tanaka, Ikkoh Funaki, Naoki Seto, Kenji Numata, Shuichia Sato, Kunihito Ioka, Nobuyuki Kanda, Takeshi Takashima, Kazuhiro Agatsuma, Tomotada Akutsu, Tomomi Akutsu, Koh-suke Aoyanagi, Koji Arai, Yuta Arase, Akito Araya, Hideki Asada, Yoichi Aso, Takeshi Chiba, Toshikazu Ebisuzaki, Motohiro Enoki, Yoshiharu Eriguchi, Masa-Katsu Fujimoto, Ryuichi Fujita, Mitsuhiro Fukushima, Toshifumi Futamase, Katsuhiko Ganzu, Tomohiro Harada, Tatsuaki Hashimoto, Kazuhiro Hayama, Wataru Hikida, Yoshiaki Himemoto, Hisashi Hirabayashi, Takashi Hiramatsu, Feng-Lei Hong, Hideyuki Horisawa, Mizuhiko Hosokawa, Kiyotomo Ichiki, Takeshi Ikegami, Kaiki T. Inoue, Koji Ishidoshiro, Hideki Ishihara, Takehiko Ishikawa, Hideharu Ishizaki, Hiroyuki Ito, Yousuke Itoh, Shogo Kamagasako, Nobuki Kawashima, Fumiko Kawazoe, Hiroyuki Kirihara, Naoko Kishimoto, Kenta Kiuche, Shiho Kobayashi, Kazunori Kohri, Hiroyuki Koizumi, Yasufumi Kojima, Keiko Kokeyama, Wataru Kokuyama, Kei Kotake, Yoshihide Kozai, Hideaki Kudoh, Hiroo Kunimori, Hitoshi Kuninaka, Kazuaki Kuroda, Kei-ichi Maeda, Hideo Matsuhara, Yasushi Mino, Osamu Miyakawa, Shinji Miyoki, Mutsuko Y. Morimoto, Tomoko Morioka, Toshiyuki Morisawa, Shigenori Moriwaki, Shinji Mukohyama, Mitsuru Musha, Shigeo Nagano, Isao Naito, Noriyasu Nakagawa, Kouji Nakamura, Hiroyuki Nakano, Kenichi Nakao, Shinichi Nakasuka, Yoshinori Nakayama, Erina Nishida, Kazutaka Nishiyama, Atsushi Nishizawa, Yoshito Niwa, Masatake Ohashi, Naoko Ohishi, Masashi Ohkawa, Akira Okutomi, Kouji Onozato, Kenichi Oohara, Norichika Sago, Motoyuki Saijo, Masaaki Sakagami, Shin-ichiro Sakai, Shihori Sakata, Misao Sasaki, Takashi Sato, Masaru Shibata, Hisaaki Shinkai, Kentaro Somiya, Hajime Sotani, Naoshi Sugiyama, Yudai Suwa, Hideyuki Tagoshi, Kakeru Takahashi, Keitaro Takahashi, Tadayuki Takahashi, Hirotaka Takahashi, Ryuichi Takahashi, Ryutaro Takahashi, Akiteru Takamori, Tadashi Takano, Keisuke Taniguchi, Atsushi Taruya, Hiroyuki Tashiro, Mitsuru Tokuda, Masao Tokunari, Morio Toyoshima, Shinji Tsujikawa, Yoshiki Tsunesada, Ken-ichi Ueda, Masayoshi Utashima, Hiroshi Yamakawa, Kazuhiro Yamamoto, Toshitaka Yamazaki, Jun'ichi Yokoyama, Chul-Moon Yoo, Shijun Yoshida, Taizoh Yoshino

TAUP2007: TENTH INTERNATIONAL CONFERENCE ON TOPICS IN ASTROPARTICLE AND UNDERGROUND PHYSICS ( IOP PUBLISHING LTD )  120   2008 [ Peer Review Accepted ]

Type of publication: Research paper (international conference proceedings)

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DECIGO pathfinder (DPF) is a milestone satellite mission for DECIGO (DECi-hertz Interferometer Gravitational wave Observatory) which is a future space gravitational wave antenna. DECIGO is expected to provide us fruitful insights into the universe, in particular about dark energy, a fori-nation mechanism of supermassive black holes, and the inflation of the universe. Since DECIGO will be an extremely large mission which will formed by three drag-free spacecraft with 1000m separation, it is significant to gain the technical feasibility of DECIGO before its planned launch in 2024. Thus, we are planning to launch two milestone missions: DPF and pre-DECIGO. The conceptual design and current status of the first milestone mission, DPF, are reviewed in this article.

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The Japanese Space Gravitational Wave Antenna; DECIGO

Seiji Kawamura, Masaki Ando, Takashi Nakamura, Kimio Tsubono, Takahiro Tanaka, Ikkoh Funaki, Naoki Seto, Kenji Numata, Shuichi Sato, Kunihito Ioka, Nobuyuki Kanda, Takeshi Takashima, Kazuhiro Agatsuma, Tomotada Akutsu, Tomomi Akutsu, Koh-suke Aoyanagi, Koji Arai, Yuta Arase, Akito Araya, Hideki Asada, Yoichi Aso, Takeshi Chiba, Toshikazu Ebisuzaki, Motohiro Enoki, Yoshiharu Eriguchi, Masa-Katsu Fujimoto, Ryuichi Fujita, Mitsuhiro Fukushima, Toshifumi Futamase, Katsuhiko Ganzu, Tomohiro Harada, Tatsuaki Hashimoto, Kazuhiro Hayama, Wataru Hikida, Yoshiaki Himemoto, Hisashi Hirabayashi, Takashi Hiramatsu, Feng-Lei Hong, Hideyuki Horisawa, Mizuhiko Hosokawa, Kiyotomo Ichiki, Takeshi Ikegami, Kaiki T. Inoue, Koji Ishidoshiro, Hideki Ishihara, Takehiko Ishikawa, Hideharu Ishizaki, Hiroyuki Ito, Yousuke Itoh, Shogo Kamagasako, Nobuki Kawashima, Fumiko Kawazoe, Hiroyuki Kirihara, Naoko Kishimoto, Kenta Kiuchi, Shiho Kobayashi, Kazunori Kohri, Hiroyuki Koizumi, Yasufumi Kojima, Keiko Kokeyama, Wataru Kokuyama, Kei Kotake, Yoshihide Kozai, Hideaki Kudoh, Hiroo Kunimori, Hitoshi Kuninaka, Kazuaki Kuroda, Kei-ichi Maeda, Hideo Matsuhara, Yasushi Mino, Osamu Miyakawa, Shinji Miyoki, Mutsuko Y. Morimoto, Tomoko Morioka, Toshiyuki Morisawa, Shigenori Moriwaki, Shinji Mukohyama, Mitsuru Musha, Shigeo Nagano, Isao Naito, Noriyasu Nakagawa, Kouji Nakamura, Hiroyuki Nakano, Kenichi Nakao, Shinichi Nakasuka, Yoshinori Nakayama, Erina Nishida, Kazutaka Nishiyama, Atsushi Nishizawa, Yoshito Niwa, Masatake Ohashi, Naoko Ohishi, Masashi Ohkawa, Akira Okutomi, Kouji Onozato, Kenichi Oohara, Norichika Sago, Motoyuki Saijo, Masaaki Sakagami, Shin-ichiro Sakai, Shihori Sakata, Misao Sasaki, Takashi Sato, Masaru Shibata, Hisaaki Shinkai, Kentaro Somiya, Hajime Sotani, Naoshi Sugiyama, Yudai Suwa, Hideyuki Tagoshi, Kakeru Takahashi, Keitaro Takahashi, Tadayuki Takahashi, Hirotaka Takahashi, Ryuichi Takahashi, Ryutaro Takahashi, Akiteru Takamori, Tadashi Takano, Keisuke Taniguchi, Atsushi Taruya, Hiroyuki Tashiro, Mitsuru Tokuda, Masao Tokunari, Morio Toyoshima, Shinji Tsujikawa, Yoshiki Tsunesada, Ken-ichi Ueda, Masayoshi Utashima, Hiroshi Yamakawa, Kazuhiro Yamamoto, Toshitaka Yamazaki, Jun'ichi Yokoyama, Chul-Moon Yoo, Shijun Yoshida, Taizoh Yoshino

TAUP2007: TENTH INTERNATIONAL CONFERENCE ON TOPICS IN ASTROPARTICLE AND UNDERGROUND PHYSICS ( IOP PUBLISHING LTD )  120   2008 [ Peer Review Accepted ]

Type of publication: Research paper (international conference proceedings)

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DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. DECIGO is expected to open a new window of observation for gravitational wave astronomy especially between 0.1 Hz and 10 Hz, revealing various mysteries of the universe such as dark energy, formation mechanism of supermassive black holes, and inflation of the universe. The pre-conceptual design of DECIGO consists of three drag-free spacecraft, whose relative displacements are measured by a differential Fabry-Perot Michelson interferometer. We plan to launch two missions, DECIGO pathfinder and pre-DECIGO first and finally DECIGO in 2024.

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Relativistic hydrodynamics in the presence of puncture black holes

Faber Joshua A., Baumgarte Thomas W., Etienne Zachariah B., Shapiro Stuart L., Taniguchi Keisuke

PHYSICAL REVIEW D ( AMER PHYSICAL SOC )  76 ( 10 )   2007.11 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Many of the recent numerical simulations of binary black holes in vacuum adopt the moving puncture approach. This successful approach avoids the need to impose numerical excision of the black hole interior and is easy to implement. Here we wish to explore how well the same approach can be applied to moving black hole punctures in the presence of relativistic hydrodynamic matter. First, we evolve single black hole punctures in vacuum to calibrate our Baumgarte-Shapiro-Shibata-Nakamura implementation and to confirm that the numerical solution for the exterior spacetime is invariant to any junk (i.e., constraint-violating) initial data employed in the black hole interior. Then we focus on relativistic Bondi accretion onto a moving puncture Schwarzschild black hole as a numerical test bed for our high-resolution shock-capturing relativistic hydrodynamics scheme. We find that the hydrodynamical equations can be evolved successfully in the interior without imposing numerical excision. These results help motivate the adoption of the moving puncture approach to treat the binary black hole-neutron star problem using conformal thin-sandwich initial data.

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Quasiequilibrium black hole-neutron star binaries in general relativity

Taniguchi Keisuke, Baumgarte Thomas W., Faber Joshua A., Shapiro Stuart L.

PHYSICAL REVIEW D ( AMER PHYSICAL SOC )  75 ( 8 )   2007.04 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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We construct quasiequilibrium sequences of black hole-neutron star binaries in general relativity. We solve Einstein's constraint equations in the conformal thin-sandwich formalism, subject to black hole boundary conditions imposed on the surface of an excised sphere, together with the relativistic equations of hydrostatic equilibrium. In contrast to our previous calculations we adopt a flat spatial background geometry and do not assume extreme mass ratios. We adopt a Gamma=2 polytropic equation of state and focus on irrotational neutron star configurations as well as approximately nonspinning black holes. We present numerical results for ratios of the black hole's irreducible mass to the neutron star's ADM mass in isolation of M-irr(BH)/M-ADM,0(NS)=1, 2, 3, 5, and 10. We consider neutron stars of baryon rest mass M-B(NS)/M-B(max) =83% and 56%, where M-B(max) is the maximum allowed rest mass of a spherical star in isolation for our equation of state. For these sequences, we locate the onset of tidal disruption and, in cases with sufficiently large mass ratios and neutron star compactions, the innermost stable circular orbit. We compare with previous results for black hole-neutron star binaries and find excellent agreement with third-order post-Newtonian results, especially for large binary separations. We also use our results to estimate the energy spectrum of the outgoing gravitational radiation emitted during the inspiral phase for these binaries.

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The final phase of inspiral of neutron stars: Realistic equations of state

Gondek-Rosinska D., Bejger M., Bulik T., Gourgoulhon E., Haensel Pawel, Limousin F., Taniguchi K., Zdunik L.

ADVANCES IN SPACE RESEARCH   39 ( 2 ) 271 - 274   2007 [ Peer Review Accepted ]

Type of publication: Research paper (international conference proceedings)

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Results of the search for inspiraling compact star binaries from TAMA300's observation in 2000-2004

Akutsu Tomomi, Akutsu Tomotada, Ando Masaki, Arai Koji, Araya Akito, Asada Hideki, Aso Youichi, Barton Mark A., Beyersdorf Peter, Fujiki Youhei, Fujimoto Masa-Katsu, Fujita Ryuichi, Fukushima Mitsuhiro, Futamase Toshifumi, Hamuro Yusaku, Haruyama Tomiyoshi, Hayakawa Hideaki, Hayama Kazuhiro, Heinzel Gerhard, Horikoshi Gen'ichi, Iguchi Hideo, Iida Yukiyoshi, Ioka Kunihito, Ishitsuka Hideki, Kamikubota Norihiko, Kanda Nobuyuki, Kaneyama Takaharu, Karasawa Yoshikazu, Kasahara Kunihiko, Kasai Taketoshi, Katsuki Mayu, Kawabe Keita, Kawamura Mari, Kawamura Seiji, Kawashima Nobuki, Kawazoe Fumiko, Kojima Yasufumi, Kokeyama Keiko, Kondo Kazuhiro, Kozai Yoshihide, Kudoh Hideaki, Kuroda Kazuaki, Kuwabara Takashi, Matsuda Namio, Mio Norikatsu, Miura Kazuyuki, Miyakawa Osamu, Miyama Shoken, Miyoki Shinji, Mizusawa Hiromi, Moriwaki Shigenori, Musha Mitsuru, Nagano Shigeo, Nagayama Yoshitaka, Nakagawa Ken'ichi, Nakamura Takashi, Nakano Hiroyuki, Nakao Ken-ichi, Nishi Yuhiko, Numata Kenji, Ogawa Yujiro, Ohashi Masatake, Ohishi Naoko, Okutomi Akira, Oohara Ken-ichi, Otsuka Shigemi, Sago Norichika, Saito Yoshio, Sakata Shihori, Sasaki Misao, Sato Kouichi, Sato Nobuaki, Sato Shuichi, Sato Youhei, Seki Hidetsugu, Sekido Aya, Seto Naoki, Shibata Masaru, Shinkai Hisaaki, Shintomi Takakazu, Soida Kenji, Somiya Kentaro, Suzuki Toshikazu, Tagoshi Hideyuki, Takahashi Hirotaka, Takahashi Ryutaro, Takamori Akiteru, Takemoto Shuzo, Takeno Kohei, Tanaka Takahiro, Taniguchi Keisuke, Taniguchi Shinsuke, Tanji Toru, Tatsumi Daisuke, Taylor C. T., Telada Souichi, Tochikubo Kuniharu, Tokunari Masao, Tomaru Takayuki, Tsubono Kimio, Tsuda Nobuhiro, Tsunesada Yoshiki, Uchiyama Takashi, Ueda Akitoshi, Ueda Ken-ichi, Usui Fumihiko, Waseda Koichi, Watanabe Yuko, Yakura Hiromi, Yamamoto Akira, Yamamoto Kazuhiro, Yamazaki Toshitaka, Yanagi Yuriko, Yoda Tatsuo, Yokoyama Jun'ichi, Yoshida Tatsuru, Zhu Zong-Hong

PHYSICAL REVIEW D ( AMER PHYSICAL SOC )  74 ( 12 )   2006.12 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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We analyze the data of the TAMA300 detector to search for gravitational waves from inspiraling compact star binaries with masses of the component stars in the range 1M-3M. In this analysis, 2705 hours of data, taken during the years 2000-2004, are used for the event search. We combine the results of different observation runs, and obtain a single upper limit on the rate of the coalescence of compact binaries in our Galaxy of 20 per year at a 90% confidence level. In this upper limit, the effects of various systematic errors such as the uncertainty of the background estimation and the calibration of the detector's sensitivity are included.

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Quasiequilibrium sequences of black-hole-neutron-star binaries in general relativity

Taniguchi Keisuke, Baumgarte Thomas W., Faber Joshua A., Shapiro Stuart L.

PHYSICAL REVIEW D ( AMER PHYSICAL SOC )  74 ( 4 )   2006.08 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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We construct quasiequilibrium sequences of black-hole-neutron-star binaries for arbitrary mass ratios by solving the constraint equations of general relativity in the conformal thin-sandwich decomposition. We model the neutron star as a stationary polytrope satisfying the relativistic equations of hydrodynamics and account for the black hole by imposing equilibrium boundary conditions on the surface of an excised sphere (the apparent horizon). In this paper we focus on irrotational configurations, meaning that both the neutron star and the black hole are approximately nonspinning in an inertial frame. We present results for a binary with polytropic index n=1, mass ratio M-irr(BH)/M-B(NS)=5, and neutron star compaction M-ADM,0(NS)/R-0=0.0879, where M-irr(BH) is the irreducible mass of the black hole, M-B(NS) the neutron star baryon rest mass, and M-ADM,0(NS) and R-0 the neutron star Arnowitt-Deser-Misner mass and areal radius in isolation, respectively. Our models represent valid solutions to Einstein's constraint equations and may therefore be employed as initial data for dynamical simulations of black-hole-neutron-star binaries.

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Joint LIGO and TAMA300 search for gravitational waves from inspiralling neutron star binaries

Abbott B., Abbott R., Adhikari R., Ageev A., Agresti J., Ajith P., Allen B., Allen J., Amin R., Anderson S. B., Anderson W. G., Araya M., Armandula H., Ashley M., Asiri F., Aufmuth P., Aulbert C., Babak S., Balasubramanian R., Ballmer S., Barish B. C., Barker C., Barker D., Barnes M., Barr B., Barton M. A., Bayer K., Beausoleil R., Belczynski K., Bennett R., Berukoff S. J., Betzwieser J., Bhawal B., Bilenko I. A., Billingsley G., Black E., Blackburn K., Blackburn L., Bland B., Bochner B., Bogue L., Bork R., Bose S., Brady P. R., Braginsky V. B., Brau J. E., Brown D. A., Bullington A., Bunkowski A., Buonanno A., Burgess R., Busby D., Butler W. E., Byer R. L., Cadonati L., Cagnoli G., Camp J. B., Cannizzo J., Cannon K., Cantley C. A., Cao J., Cardenas L., Carter K., Casey M. M., Castiglione J., Chandler A., Chapsky J., Charlton P., Chatterji S., Chelkowski S., Chen Y., Chickarmane V., Chin D., Christensen N., Churches D., Cokelaer T., Colacino C., Coldwell R., Coles M., Cook D., Corbitt T., Coyne D., Creighton J. D. E., Creighton T. D., Crooks D. R. M., Csatorday P., Cusack B. J., Cutler C., Dalrymple J., D'Ambrosio E., Danzmann K., Davies G., Daw E., DeBra D., Delker T., Dergachev V., Desai S., DeSalvo R., Dhurandhar S., Di Credico A., Diaz M., Ding H., Drever R. W. P., Dupuis R. J., Edlund J. A., Ehrens P., Elliffe E. J., Etzel T., Evans M., Evans T., Fairhurst S., Fallnich C., Farnham D., Fejer M. M., Findley T., Fine M., Finn L. S., Franzen K. Y., Freise A., Frey R., Fritschel P., Frolov V. V., Fyffe M., Ganezer K. S., Garofoli J., Giaime J. A., Gillespie A., Goda K., Goggin L., Gonzalez G., Gossler S., Grandclement P., Grant A., Gray C., Gretarsson A. M., Grimmett D., Grote H., Grunewald S., Guenther M., Gustafson E., Gustafson R., Hamilton W. O., Hammond M., Hanna C., Hanson J., Hardham C., Harms J., Harry G., Hartunian A., Heefner J., Hefetz Y., Heinzel G., Heng I. S., Hennessy M., Hepler N., Heptonstall A., Heurs M., Hewitson M., Hild S., Hindman N., Hoang P., Hough J., Hrynevych M., Hua W., Ito M., Itoh Y., Ivanov A., Jennrich O., Johnson B., Johnson W. W., Johnston W. R., Jones D. I., Jones G., Jones L., Jungwirth D., Kalogera V., Katsavounidis E., Kawabe K., Kells W., Kern J., Khan A., Killbourn S., Killow C. J., Kim C., King C., King P., Klimenko S., Koranda S., Koetter K., Kovalik J., Kozak D., Krishnan B., Landry M., Langdale J., Lantz B., Lawrence R., Lazzarini A., Lei M., Leonor I., Libbrecht K., Libson A., Lindquist P., Liu S., Logan J., Lormand M., Lubinski M., Lueck H., Luna M., Lyons T. T., Machenschalk B., MacInnis M., Mageswaran M., Mailand K., Majid W., Malec M., Mandic V., Mann F., Marin A., Marka S., Maros E., Mason J., Mason K., Matherny O., Matone L., Mavalvala N., McCarthy R., McClelland D. E., McHugh M., McNabb J. W. C., Melissinos A., Mendell G., Mercer R. A., Meshkov S., Messaritaki E., Messenger C., Mikhailov E., Mitra S., Mitrofanov V. P., Mitselmakher G., Mittleman R., Miyakawa O., Mohanty S., Moreno G., Mossavi K., Mueller G., Mukherjee S., Murray P., Myers E., Myers J., Nagano S., Nash T., Nayak R., Newton G., Nocera F., Noel J. S., Nutzman P., Olson T., O'Reilly B., Ottaway D. J., Ottewill A., Ouimette D., Overmier H., Owen B. J., Pan Y., Papa M. A., Parameshwaraiah V., Parameswariah C., Pedraza M., Penn S., Pitkin M., Plissi M., Prix R., Quetschke V., Raab F., Radkins H., Rahkola R., Rakhmanov M., Rao S. R., Rawlins K., Ray-Majumder S., Re V., Redding D., Regehr M. W., Regimbau T., Reid S., Reilly K. T., Reithmaier K., Reitze D. H., Richman S., Riesen R., Riles K., Rivera B., Rizzi A., Robertson D. I., Robertson N. A., Robinson C., Robison L., Roddy S., Rodriguez A., Rollins J., Romano J. D., Romie J., Rong H., Rose D., Rotthoff E., Rowan S., Ruediger A., Ruet L., Russell P., Ryan K., Salzman I., Sandberg V., Sanders G. H., Sannibale V., Sarin P., Sathyaprakash B., Saulson P. R., Savage R., Sazonov A., Schilling R., Schlaufman K., Schmidt V., Schnabel R., Schofield R., Schutz B. F., Schwinberg P., Scott S. M., Seader S. E., Searle A. C., Sears B., Seel S., Seifert F., Sellers D., Sengupta A. S., Shapiro C. A., Shawhan P., Shoemaker D. H., Shu Q. Z., Sibley A., Siemens X., Sievers L., Sigg D., Sintes A. M., Smith J. R., Smith M., Smith M. R., Sneddon P. H., Spero R., Spjeld O., Stapfer G., Steussy D., Strain K. A., Strom D., Stuver A., Summerscales T., Sumner M. C., Sung M., Sutton P. J., Sylvestre J., Tanner D. B., Tariq H., Tarallo M., Taylor I., Taylor R., Taylor R., Thorne K. A., Thorne K. S., Tibbits M., Tilav S., Tinto M., Tokmakov K. V., Torres C., Torrie C., Traylor G., Tyler W., Ugolini D., Ungarelli C., Vallisneri M., van Putten M., Vass S., Vecchio A., Veitch J., Vorvick C., Vyachanin S. P., Wallace L., Walther H., Ward H., Ward R., Ware B., Watts K., Webber D., Weidner A., Weiland U., Weinstein A., Weiss R., Welling H., Wen L., Wen S., Wette K., Whelan J. T., Whitcomb S. E., Whiting B. F., Wiley S., Wilkinson C., Willems P. A., Williams P. R., Williams R., Willke B., Wilson A., Winjum B. J., Winkler W., Wise S., Wiseman A. G., Woan G., Woods D., Wooley R., Worden J., Wu W., Yakushin I., Yamamoto H., Yoshida S., Zaleski K. D., Zanolin M., Zawischa I., Zhang L., Zhu R., Zotov N., Zucker M., Zweizig J., Akutsu T., Akutsu T., Ando M., Arai K., Araya A., Asada H., Aso Y., Beyersdorf P., Fujiki Y., Fujimoto M. -K., Fujita R., Fukushima M., Futamase T., Hamuro Y., Haruyama T., Hayama K., Iguchi H., Iida Y., Ioka K., Ishitsuka H., Kamikubota N., Kanda N., Kaneyama T., Karasawa Y., Kasahara K., Kasai T., Katsuki M., Kawamura S., Kawamura M., Kawazoe F., Kojima Y., Kokeyama K., Kondo K., Kozai Y., Kudoh H., Kuroda K., Kuwabara T., Matsuda N., Mio N., Miura K., Miyama S., Miyoki S., Mizusawa H., Moriwaki S., Musha M., Nagayama Y., Nakagawa K., Nakamura T., Nakano H., Nakao K., Nishi Y., Numata K., Ogawa Y., Ohashi M., Ohishi N., Okutomi A., Oohara K., Otsuka S., Saito Y., Sakata S., Sasaki M., Sato N., Sato S., Sato Y., Sato K., Sekido A., Seto N., Shibata M., Shinkai H., Shintomi T., Soida K., Somiya K., Suzuki T., Tagoshi H., Takahashi H., Takahashi R., Takamori A., Takemoto S., Takeno K., Tanaka T., Taniguchi K., Tanji T., Tatsumi D., Telada S., Tokunari M., Tomaru T., Tsubono K., Tsuda N., Tsunesada Y., Uchiyama T., Ueda K., Ueda A., Waseda K., Yamamoto A., Yamamoto K., Yamazaki T., Yanagi Y., Yokoyama J., Yoshida T., Zhu Z. -H.

PHYSICAL REVIEW D ( American Physical Society (APS) )  73 ( 10 ) 102002   2006.05 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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The Japanese space gravitational wave antenna - DECIGO

Kawamura Seiji, Nakamura Takashi, Ando Masaki, Seto Naoki, Tsubono Kimio, Numata Kenji, Takahashi Ryuichi, Nagano Shigeo, Ishikawa Takehiko, Musha Mitsuru, Ueda Ken-ichi, Sato Takashi, Hosokawa Mizuhiko, Agatsuma Kazuhiro, Akutsu Tomotada, Aoyanagi Koh-suke, Arai Koji, Araya Akito, Asada Hideki, Aso Yoichi, Chiba Takeshi, Ebisuzaki Toshikazu, Eriguchi Yoshiharu, Fujimoto Masa-Katsu, Fukushima Mitsuhiro, Futamase Toshifumi, Ganzu Katsuhiko, Harada Tomohiro, Hashimoto Tatsuaki, Hayama Kazuhiro, Hikida Wataru, Himemoto Yoshiaki, Hirabayashi Hisashi, Hiramatsu Takashi, Ichiki Kiyotomo, Ikegami Takeshi, Inoue Kaiki T., Ioka Kunihito, Ishidoshiro Koji, Itoh Yousuke, Kamagasako Shogo, Kanda Nobuyuki, Kawashima Nobuki, Kirihara Hiroyuki, Kiuchi Kenta, Kobayashi Shiho, Kohri Kazunori, Kojima Yasufumi, Kokeyama Keiko, Kozai Yoshihide, Kudoh Hideaki, Kunimori Hiroo, Kuroda Kazuaki, Maeda Kei-ichi, Matsuhara Hideo, Mino Yasushi, Miyakawa Osamu, Miyoki Shinji, Mizusawa Hiromi, Morisawa Toshiyuki, Mukohyama Shinji, Naito Isao, Nakagawa Noriyasu, Nakamura Kouji, Nakano Hiroyuki, Nishizawa Atsushi, Niwa Yoshito, Nozawa Choetsu, Ohashi Masatake, Ohishi Naoko, Ohkawa Masashi, Okutomi Akira, Oohara Kenichi, Sago Norichika, Saijo Motoyuki, Sakagami Masaaki, Sakata Shihori, Sasaki Misao, Sato Shuichi, Shibata Masaru, Shinkai Hisaaki, Somiya Kentaro, Sotani Hajime, Sugiyama Naoshi, Tagoshi Hideyuki, Takahashi Tadayuki, Takahashi Hirotaka, Takahashi Ryutaro, Takano Tadashi, Tanaka Takahiro, Taniguchi Keisuke, Taruya Atsushi, Tashiro Hiroyuki, Tokunari Masao, Tsujikawa Shinji, Tsunesada Yoshiki, Yamamoto Kazuhiro, Yamazaki Toshitaka, Yokoyama Jun'ichi, Yoo Chul-Moon, Yoshida Shijun, Yoshino Taizoh

CLASSICAL AND QUANTUM GRAVITY ( IOP PUBLISHING LTD )  23 ( 8 ) S125 - S131   2006.04 [ Peer Review Accepted ]

Type of publication: Research paper (international conference proceedings)

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DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. It aims at detecting various kinds of gravitational waves between 1 mHz and 100 Hz frequently enough to open a new window of observation for gravitational wave astronomy. The preconceptual design of DECIGO consists of three drag-free satellites, 1000 km apart from each other, whose relative displacements are measured by a Fabry-Perot Michelson interferometer. We plan to launch DECIGO in 2024 after a long and intense development phase, including two pathfinder missions for verification of required technologies.

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General relativistic binary merger simulations and short gamma-ray bursts

Faber JA, Baumgarte TW, Shapiro SL, Taniguchi K

ASTROPHYSICAL JOURNAL   641 ( 2 ) L93 - L96   2006.04 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

General Relativistic Binary Merger Simulations and Short Gamma-Ray Bursts

Joshua A. Faber, Thomas W. Baumgarte, Stuart L. Shapiro, Keisuke Taniguchi

The Astrophysical Journal Letters   641 ( 2 ) L93 - L96   2006.04 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Merger of binary neutron stars to a black hole: Disk mass, short gamma-ray bursts, and quasinormal mode ringing

Shibata M, Taniguchi K

PHYSICAL REVIEW D ( American Physical Society (APS) )  73 ( 6 ) 064027   2006.03 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Dynamical evolution of black hole-neutron star binaries in general relativity: Simulations of tidal disruption

Faber JA, Baumgarte TW, Shapiro SL, Taniguchi K, Rasio FA

PHYSICAL REVIEW D ( American Physical Society (APS) )  73 ( 2 ) 024012   2006.01 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Upper limits from the LIGO and TAMA detectors on the rate of gravitational-wave bursts

Abbott B, Abbott R, Adhikari R, Ageev A, Agresti J, Ajith P, Allen B, Allen J, Amin R, Anderson SB, Anderson WG, Araya M, Armandula H, Ashley M, Asiri F, Aufmuth P, Aulbert C, Babak S, Balasubramanian R, Ballmer S, Barish BC, Barker C, Barker D, Barnes M, Barr B, Barton MA, Bayer K, Beausoleil R, Belczynski K, Bennett R, Berukoff SJ, Betzwieser J, Bhawal B, Bilenko IA, Billingsley G, Black E, Blackburn K, Blackburn L, Bland B, Bochner B, Bogue L, Bork R, Bose S, Brady PR, Braginsky VB, Brau JE, Brown DA, Bullington A, Bunkowski A, Buonanno A, Burgess R, Busby D, Butler WE, Byer RL, Cadonati L, Cagnoli G, Camp JB, Cannizzo J, Cannon K, Cantley CA, Cao J, Cardenas L, Carter K, Casey MM, Castiglione J, Chandler A, Chapsky J, Charlton P, Chatterji S, Chelkowski S, Chen Y, Chickarmane V, Chin D, Christensen N, Churches D, Cokelaer T, Colacino C, Coldwell R, Coles M, Cook D, Corbitt T, Coyne D, Creighton JDE, Creighton TD, Crooks DRM, Csatorday P, Cusack BJ, Cutler C, Dalrymple J, D'Ambrosio E, Danzmann K, Davies G, Daw E, DeBra D, Delker T, Dergachev V, Desai S, DeSalvo R, Dhurandhar S, Di Credico A, Diaz M, Ding H, Drever RWP, Dupuis RJ, Edlund JA, Ehrens P, Elliffe EJ, Etzel T, Evans M, Evans T, Fairhurst S, Fallnich C, Farnham D, Fejer MM, Findley T, Fine M, Finn LS, Franzen KY, Freise A, Frey R, Fritschel P, Frolov VV, Fyffe M, Ganezer KS, Garofoli J, Giaime JA, Gillespie A, Goda K, Goggin L, Gonzalez G, Gossler S, Grandclement P, Grant A, Gray C, Gretarsson AM, Grimmett D, Grote H, Grunewald S, Guenther M, Gustafson E, Gustafson R, Hamilton WO, Hammond M, Hanna C, Hanson J, Hardham C, Harms J, Harry G, Hartunian A, Heefner J, Hefetz Y, Heinzel G, Heng IS, Hennessy M, Hepler N, Heptonstall A, Heurs M, Hewitson M, Hild S, Hindman N, Hoang P, Hough J, Hrynevych M, Hua W, Ito M, Itoh Y, Ivanov A, Jennrich O, Johnson B, Johnson WW, Johnston WR, Jones DI, Jones G, Jones L, Jungwirth D, Kalogera V, Katsavounidis E, Kawabe K, Kells W, Kern J, Khan A, Killbourn S, Killow CJ, Kim C, King C, King P, Klimenko S, Koranda S, Kotter K, Kovalik J, Kozak D, Krishnan B, Landry M, Langdale J, Lantz B, Lawrence R, Lazzarini A, Lei M, Leonor I, Libbrecht K, Libson A, Lindquist P, Liu S, Logan J, Lormand M, Lubinski M, Luck H, Luna M, Lyons TT, Machenschalk B, MacInnis M, Mageswaran M, Mailand K, Majid W, Malec M, Mandic V, Mann F, Marin A, Marka S, Maros E, Mason J, Mason K, Matherny O, Matone L, Mavalvala N, McCarthy R, McClelland DE, McHugh M, McNabb JWC, Melissinos A, Mendell G, Mercer RA, Meshkov S, Messaritaki E, Messenger C, Mikhailov E, Mitra S, Mitrofanov VP, Mitselmakher G, Mittleman R, Miyakawa O, Mohanty S, Moreno G, Mossavi K, Mueller G, Mukherjee S, Murray P, Myers E, Myers J, Nagano S, Nash T, Nayak R, Newton G, Nocera F, Noel JS, Nutzman P, Olson T, O'Reilly B, Ottaway DJ, Ottewill A, Ouimette D, Overmier H, Owen BJ, Pan Y, Papa MA, Parameshwaraiah V, Parameswariah C, Pedraza M, Penn S, Pitkin M, Plissi M, Prix R, Quetschke V, Raab F, Radkins H, Rahkola 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M, Tilav S, Tinto M, Tokmakov KV, Torres C, Torrie C, Traylor G, Tyler W, Ugolini D, Ungarelli C, Vallisneri M, van Putten M, Vass S, Vecchio A, Veitch J, Vorvick C, Vyachanin SP, Wallace L, Walther H, Ward H, Ward R, Ware B, Watts K, Webber D, Weidner A, Weiland U, Weinstein A, Weiss R, Welling H, Wen L, Wen S, Wette K, Whelan JT, Whitcomb SE, Whiting BF, Wiley S, Wilkinson C, Willems PA, Williams PR, Williams R, Willke B, Wilson A, Winjum BJ, Winkler W, Wise S, Wiseman AG, Woan G, Woods D, Wooley R, Worden J, Wu W, Yakushin I, Yamamoto H, Yoshida S, Zaleski KD, Zanolin M, Zawischa I, Zhang L, Zhu R, Zotov N, Zucker M, Zweizig J, Akutsu T, Akutsu T, Ando M, Arai K, Araya A, Asada H, Aso Y, Beyersdorf P, Fujiki Y, Fujimoto MK, Fujita R, Fukushima M, Futamase T, Hamuro Y, Haruyama T, Hayama K, Iguchi H, Iida Y, Ioka K, Ishizuka H, Kamikubota N, Kanda N, Kaneyama T, Karasawa Y, Kasahara K, Kasai T, Katsuki M, Kawamura S, Kawamura M, Kawazoe F, Kojima Y, Kokeyama K, Kondo K, Kozai Y, Kudoh H, Kuroda K, Kuwabara T, Matsuda N, Mio N, Miura K, Miyama S, Miyoki S, Mizusawa H, Moriwaki S, Musha M, Nagayama Y, Nakagawa K, Nakamura T, Nakano H, Nakao K, Nishi Y, Numata K, Ogawa Y, Ohashi M, Ohishi N, Okutomi A, Oohara K, Otsuka S, Saito Y, Sakata S, Sasaki M, Sato N, Sato S, Sato Y, Sato K, Sekido A, Seto N, Shibata M, Shinkai H, Shintomi T, Soida K, Somiya K, Suzuki T, Tagoshi H, Takahashi H, Takahashi R, Takamori A, Takemoto S, Takeno K, Tanaka T, Taniguchi K, Tanji T, Tatsumi D, Telada S, Tokunari M, Tomaru T, Tsubono K, Tsuda N, Tsunesada Y, Uchiyama T, Ueda K, Ueda A, Waseda K, Yamamoto A, Yamamoto K, Yamazaki T, Yanagi Y, Yokoyama J, Yoshida T, Zhu ZH

PHYSICAL REVIEW D ( American Physical Society (APS) )  72 ( 12 ) 122004   2005.12 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Black hole-neutron star binaries in general relativity: Effects of neutron star spin

Taniguchi K, Baumgarte TW, Faber JA, Shapiro SL

PHYSICAL REVIEW D ( American Physical Society (APS) )  72 ( 4 ) 044008   2005.08 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Merger of binary neutron stars with realistic equations of state in full general relativity

Shibata M, Taniguchi K, Uryu K

PHYSICAL REVIEW D ( American Physical Society (APS) )  71 ( 8 ) 084021   2005.04 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Observation results by the TAMA300 detector on gravitational wave bursts from stellar-core collapses

Ando M, Arai K, Aso Y, Beyersdorf P, Hayama K, Iida Y, Kanda N, Kawamura S, Kondo K, Mio N, Miyoki S, Moriwaki S, Nagano S, Numata K, Sato S, Somiya K, Tagoshi H, Takahashi H, Takahashi R, Tatsumi D, Tsunesada Y, Zhu ZH, Akutsu T, Akutsu T, Araya A, Asada H, Barton MA, Fujiki Y, Fujimoto MK, Fujita R, Fukushima M, Futamase T, Hamuro Y, Haruyama T, Hayakawa H, Heinzel G, Horikoshi G, Iguchi H, Ioka K, Ishitsuka H, Kamikubota N, Kaneyama T, Karasawa Y, Kasahara K, Kasai T, Katsuki M, Kawabe K, Kawamura M, Kawashima N, Kawazoe F, Kojima Y, Kokeyama K, Kozai Y, Kudoh H, Kuroda K, Kuwabara T, Matsuda N, Miura K, Miyakawa O, Miyama S, Mizusawa H, Musha M, Nagayama Y, Nakagawa K, Nakamura T, Nakano H, Nakao K, Nishi Y, Ogawa Y, Ohashi M, Ohishi N, Okutomi A, Oohara K, Otsuka S, Saito Y, Sakata S, Sasaki M, Sato K, Sato N, Sato Y, Seki H, Sekido A, Seto N, Shibata M, Shinkai H, Shintomi T, Soida K, Suzuki T, Takamori A, Takemoto S, Takeno K, Tanaka T, Taniguchi K, Taniguchi S, Tanji T, Taylor CT, Telada S, Tochikubo K, Tokunari M, Tomaru T, Tsubono K, Tsuda N, Uchiyama T, Ueda A, Ueda K, Usui F, Waseda K, Watanabe Y, Yakura H, Yamamoto A, Yamamoto K, Yamazaki T, Yanagi Y, Yoda T, Yokoyama J, Yoshida T

PHYSICAL REVIEW D ( American Physical Society (APS) )  71 ( 8 ) 082002   2005.04 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Impact of the nuclear equation of state on the last orbits of binary neutron stars

Bejger M, Gondek-Rosinska D, Gourgoulhon E, Haensel P, Taniguchi K, Zdunik JL

ASTRONOMY & ASTROPHYSICS ( EDP Sciences )  431 ( 1 ) 297 - 306   2005.02 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Various features of quasiequilibrium sequences of binary neutron stars in general relativity

Taniguchi K, Gourgoulhon E

PHYSICAL REVIEW D ( American Physical Society (APS) )  68 ( 12 ) 124025   2003.12 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Merger of binary neutron stars of unequal mass in full general relativity

Shibata M, Taniguchi K, Uryu K

PHYSICAL REVIEW D ( American Physical Society (APS) )  68 ( 8 ) 084020   2003.10 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Measuring neutron-star radii with gravitational-wave detectors

Faber JA, Grandclement P, Rasio FA, Taniguchi K

PHYSICAL REVIEW LETTERS ( American Physical Society (APS) )  89 ( 23 ) 231102   2002.12 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Quasiequilibrium sequences of synchronized and irrotational binary neutron stars in general relativity. III. Identical and different mass stars with gamma=2

Taniguchi K, Gourgoulhon E

PHYSICAL REVIEW D ( American Physical Society (APS) )  66 ( 10 ) 104019   2002.11 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Equilibrium sequences of synchronized and irrotational binary systems composed of different mass stars in Newtonian gravity

Taniguchi K, Gourgoulhon E

PHYSICAL REVIEW D ( American Physical Society (APS) )  65 ( 4 ) 044027   2002.02 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Quasiequilibrium sequences of synchronized and irrotational binary neutron stars in general relativity. II. Newtonian limits

Keisuke Taniguchi, Eric Gourgoulhon, Silvano Bonazzola

Physical Review D ( American Physical Society (APS) )  64 ( 6 ) 064012   2001.08 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Quasiequilibrium sequences of synchronized and irrotational binary neutron stars in general relativity: Method and tests

Eric Gourgoulhon, Philippe Grandclément, Keisuke Taniguchi, Jean-Alain Marck, Silvano Bonazzola

Physical Review D ( American Physical Society (APS) )  63 ( 6 ) 064029   2001.02 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Equilibrium sequences of irrotational binary polytropic sears: The case of double polytropic stars

Taniguchi K, Nakamura T

PHYSICAL REVIEW D   62 ( 4 )   2000.08 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Gravitational waves from inspiraling compact binaries with magnetic dipole moments

Ioka K, Taniguchi K

ASTROPHYSICAL JOURNAL   537 ( 1 ) 327 - 333   2000.07 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Almost analytic solutions to equilibrium sequences of irrotational binary polytropic stars for n=1

Taniguchi K, Nakamura T

PHYSICAL REVIEW LETTERS   84 ( 4 ) 581 - 585   2000.01 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Irrotational and incompressible ellipsoids in the first post-newtonian approximation of general relativity (vol 100, pg 703, 1998)

Taniguchi K, Asada H, Shibata M

PROGRESS OF THEORETICAL PHYSICS   101 ( 3 ) 781 - 782   1999.03 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Irrotational and incompressible binary systems in the first post-Newtonian approximation of general relativity

Taniguchi K

PROGRESS OF THEORETICAL PHYSICS   101 ( 2 ) 283 - 328   1999.02 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Gravitational radiation from corotating binary neutron stars of incompressible fluid in the first post-Newtonian approximation of general relativity

Taniguchi K, Shibata M

PHYSICAL REVIEW D   58 ( 8 )   1998.10 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Irrotational and incompressible ellipsoids in the first post-Newtonian approximation of general relativity

Taniguchi K, Asada H, Shibata M

PROGRESS OF THEORETICAL PHYSICS   100 ( 4 ) 703 - 735   1998.10 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Solving the Darwin problem in the first post-Newtonian approximation of general relativity

Taniguchi K, Shibata M

PHYSICAL REVIEW D   56 ( 2 ) 798 - 810   1997.07 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Solving the Darwin problem in the first post-Newtonian approximation of general relativity: Compressible model

Shibata M, Taniguchi K

PHYSICAL REVIEW D   56 ( 2 ) 811 - 825   1997.07 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Innermost stable circular orbit of coalescing neutron star-black hole binary - Generalized pseudo-Newtonian potential approach

Taniguchi K, Nakamura T

PROGRESS OF THEORETICAL PHYSICS   96 ( 4 ) 693 - 712   1996.10 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)