vol. 77 | iTHES

Vol. 77, April 20th, 2015

TABLE OF CONTENTS

  • Upcoming Events
  • Paper of the week

Paper of the week

Yuichiro Sekiguchi, Kenta Kiuchi, Koutarou Kyutoku, Masaru Shibata

photo

"Dynamical mass ejection from binary neutron star mergers: radiation-hydrodynamics study in general relativity"

From the Office

The office of iTHES assistant, Ms.Chikako Oota is situated at the second floor of the main research building, room # 246. The extension number is 3261. She will be at the office from 10 a.m. to 16 p.m.

Upcoming Events


iTHES Seminar
Speaker: Toshikazu Ebisuzaki (RIKEN Computational Astrophysics Laboratory)
Title: Accretion Disk around a protostar and Planet Formation
Date & Time: 24th April, 14:00-15:00
Place: Room 248, Main Research Building
Language: English


May 12 (Tues) 13:30-17:00
The 5th iTHES Academic-Industrial Lecture:
"Artificial Intelligence : Present and Future"
(talks in Japanese, slides in English)

schedule:
13:30-14:30 Yutaka Matsuo (Univ. Tokyo) Deep learning: present and future
http://ymatsuo.com/index.html
14:30-14:45 Break
14:45-15:45 Hiroshi Yamakawa (dwango) Generalized AI and whole-brain architecture
http://info.dwango.co.jp/english/index.html
15:45-16:00 Break
16:00-17:00 Koichi Takahashi (QBiC) AI and Science/Technology
http://www.riken.jp/en/research/labs/qbic/comput_biol/biochem_sim/
Place: Okochi Hall

Paper of the week


Yuichiro Sekiguchi, Kenta Kiuchi, Koutarou Kyutoku, Masaru Shibata
"Dynamical mass ejection from binary neutron star mergers: radiation-hydrodynamics study in general relativity"
Phys. Rev. D 91, 064059 (2015), arXiv:1502.06660
We report results of fully general relativistic simulations for binary neutron star mergers, which incorporate both neutrino cooling and heating (i.e., neutrino emission and absorption by material, respectively) for the first time in the context of the binary merger. Binary neutron stars merge due to gravitational radiation reaction, and the merger often leaves a hot and massive neutron star. Because its temperature reaches a few tens of MeV, a copious amount of thermal neutrinos are emitted. At the same time, an appreciable amount (1% of the solar mass) of neutron-rich material can be ejected by (hydro)dynamical processes during the merger. We find that the electron fraction of ejecta can increase from the value of cold material due to positron capture and electron-neutrino irradiation. As a result, the ejecta material exhibit a broad range of electron fraction extending from 0.1 to 0.45. This broad distribution is advantageous to reproduce the solar abundance of r-process elements in a single event, where the nucleosynthesis in the ejecta is studied in a separated paper [Wanajo et al., Astrophys. J. 789, L39 (2014)].