383 citations · 3.2k across the 50 of their papers we have counts for
50 papers
Prompt emission from the counter jet of a short gamma-ray burst
Ryo Yamazaki, Kunihito Ioka, Takashi Nakamura
The counter jet of a short gamma-ray burst (sGRB) has not yet been observed, while recent discoveries of gravitational waves (GWs) from a binary neutron star (NS) merger GW170817 a…
Scattered Short Gamma-Ray Bursts as Electromagnetic Counterparts to Gravitational Waves and Implications of GW170817 and GRB 170817A
Shota Kisaka, Kunihito Ioka, Kazumi Kashiyama +1
In the faint short gamma-ray burst sGRB 170817A followed by the gravitational waves (GWs) from a merger of two neutron stars (NSs) GW170817, the spectral peak energy is too high to…
Can an Off-axis Gamma-Ray Burst Jet in GW170817 Explain All the Electromagnetic Counterparts?
Kunihito Ioka, Takashi Nakamura
Gravitational waves from a merger of two neutron stars (NSs) were discovered for the first time in GW170817, together with diverse electromagnetic (EM) counterparts. To make constr…
Pre-DECIGO can get the smoking gun to decide the astrophysical or cosmological origin of GW150914-like binary black holes
Takashi Nakamura, Masaki Ando, Tomoya Kinugawa +9
Pre-DECIGO consists of three spacecraft arranged in an equilateral triangle with 100km arm lengths orbiting 2000km above the surface of the earth. It is hoped that the launch date…
Estimate of the radius responsible for quasinormal modes in the extreme Kerr limit and asymptotic behavior of the Sasaki-Nakamura transformation
Hiroyuki Nakano, Norichika Sago, Takahiro Tanaka +1
The Sasaki-Nakamura transformation gives a short-ranged potential and a convergent source term for the master equation of perturbations in the Kerr space-time. In this paper, we st…
The detection of Quasinormal Mode of Pop III Binary Black Hole merger with final and would confirm the strong gravity space-time around which is only times the event horizon radius
Takashi Nakamura, Hiroyuki Nakano, Takahiro Tanaka
Recent population synthesis simulations of Pop III stars suggest that the event rate of coalescence of -- binary black holes can be high enough for the d…
Isotropic Detectable X-ray Counterparts to Gravitational Waves from Neutron Star Binary Mergers
Shota Kisaka, Kunihito Ioka, Takashi Nakamura
Neutron star binary mergers are strong sources of gravitational waves (GWs). Promising electromagnetic counterparts are short gamma-ray bursts (GRBs) but the emission is highly col…
Can direct collapse black holes launch gamma-ray bursts and grow to supermassive black holes?
Tatsuya Matsumoto, Daisuke Nakauchi, Kunihito Ioka +2
The existence of black holes (BHs) of mass ~ 10^{9} M_sun at z > 6 is a big puzzle in astrophysics because even optimistic estimates of the accretion time are insufficient for stel…
X-raying extended emission and rapid decay of short gamma-ray bursts
Yasuaki Kagawa, Daisuke Yonetoku, Tatsuya Sawano +5
Extended emission is a mystery in short gamma-ray bursts (SGRBs). By making time resolved spectral analyses of brightest nine events observed by XRT, we obviously cla…
Detectability of bigravity with graviton oscillations using gravitational wave observations
Tatsuya Narikawa, Koh Ueno, Hideyuki Tagoshi +3
The gravitational waveforms in the ghost-free bigravity theory exhibit deviations from those in general relativity. The main difference is caused by graviton oscillations in the bi…
Synchrotron X-ray Spectroscopy Study on the Valence State in alpha- and beta-YbAlB4 at Low Temperatures and High Magnetic Fields
Y. H. Matsuda, T. Nakamura, K. Kuga +5
The valence state of Yb ions in beta-YbAlB4 and its polymorph alpha-YbAlB4 has been investigated by using X-ray absorption and emission spectroscopy in SPring-8 at temperatures fro…
Possible existence of viable models of bi-gravity with detectable graviton oscillations by gravitational wave detectors
Antonio De Felice, Takashi Nakamura, Takahiro Tanaka
We discuss graviton oscillations based on the ghost free bi-gravity theory. We point out that this theory possesses a natural cosmological background solution which is very close t…
Long Duration X-Ray Flash and X-Ray Rich Gamma Ray Burst from Low Mass Population III Star
Daisuke Nakauchi, Yudai Suwa, Takanori Sakamoto +2
Recent numerical simulations suggest that Population III (Pop III) stars were born with masses not larger than but typically . By self-consis…
Gamma-Ray Bursts are precise distance indicators similar to Type Ia Supernovae?
Ryo Tsutsui, Takashi Nakamura, Daisuke Yonetoku +2
We estimate the distance modulus to long gamma-ray bursts (LGRBs) using the Type I Fundamental Plane, a correlation between the spectral peak energy , the peak luminosit…
JASMIN: Japanese-American study of muon interactions and neutron detection
Hiroshi Nakashima, N. V. Mokhov, Yoshimi Kasugai +22
Experimental studies of shielding and radiation effects at Fermi National Accelerator Laboratory (FNAL) have been carried out under collaboration between FNAL and Japan, aiming at…
Identification of 45 New Neutron-Rich Isotopes Produced by In-Flight Fission of a 238U Beam at 345 MeV/nucleon
Tetsuya Ohnishi, Toshiyuki Kubo*, Kensuke Kusaka +57
A search for new isotopes using in-flight fission of a 345 MeV/nucleon 238U beam has been carried out at the RI Beam Factory at the RIKEN Nishina Center. Fission fragments were ana…
Unstable GRB photospheres and electron-positron annihilation lines
Kunihito Ioka, Kohta Murase, Kenji Toma +2
We propose an emission mechanism of prompt gamma-ray bursts (GRBs) that can reproduce the observed non-thermal spectra with high radiative efficiencies, >50%. Internal dissipation…
Low-Luminosity GRB 060218: A Collapsar Jet from a Neutron Star, Leaving a Magnetar as a Remnant?
Kenji Toma, Kunihito Ioka, Takanori Sakamoto +1
The gamma-ray burst (GRB) 060218 has ~ 10^5 times lower luminosity than typical long GRBs, and is associated with a supernova (SN). The radio afterglow displays no jet break, so th…
High Energy Neutrinos and Cosmic-Rays from Low-Luminosity Gamma-Ray Bursts?
Kohta Murase, Kunihito Ioka, Shigehiro Nagataki +1
The recently discovered gamma-ray burst (GRB) GRB 060218/SN 2006aj is classified as an X-ray Flash with very long duration driven possibly by a neutron star. Since GRB 060218 is ve…
Ep-Eiso Correlation in a Multiple Subjet Model of Gamma-Ray Bursts
Kenji Toma, Ryo Yamazaki, Takashi Nakamura
We perform Monte Carlo simulations to study Ep-Eiso correlation in the context of a multiple subjet model (or inhomogeneous jet model) for gamma-ray bursts (GRBs), X-ray--rich GRBs…
Evidence for Direct CP Violation in B0 -> K+- pi-+ Decays
Y. Chao
We report evidence for direct CP violation in the decay B0 -> K+-pi-+ with 253/fb of data collected with the Belle detector at the KEKB e+e- collider. Using 275 million B B_bar pai…
Improved Measurement of Mixing-induced CP Violation in the Neutral B Meson System
The Belle Collaboration, K. Abe
We present an improved measurement of the standard model CP violation parameter sin2phi_1 (also known as sin2beta) based on a sample of 85 times 10^6 B Bbar pairs collected at the…
Possible Origin of Lognormal Distributions in Gamma-Ray Bursts
Kunihito Ioka, Takashi Nakamura
We show that if the intrinsic break energy of Gamma-Ray Bursts (GRBs) is determined by the product of more than three random variables the observed break energy distribution become…
Is dark energy the only solution to the apparent acceleration of the present universe?
Hideo Iguchi, Takashi Nakamura, Ken-ichi Nakao
Even for the observed luminosity distance D_L(z), which suggests the existence of dark energy, we show that an inhomogeneous dust universe solution without dark energy is possible…