Free Neutron Ejection from Shock Breakout in Binary Neutron Star Mergers

Ayako Ishii, Toshikazu Shigeyama, Masaomi Tanaka

研究成果: Article査読

9 被引用数 (Scopus)


Merging neutron stars generate shock waves that disintegrate heavy nuclei into nucleons, especially in the outer envelope. It is expected that some of these neutrons, having avoided capturing positrons, remain as free neutrons even after the disappearance of electron-positron pairs. To investigate how many free neutrons can be ejected from merging neutron stars, we performed special-relativistic Lagrangian hydrodynamics computations with simplified models of this phenomenon in which a spherically symmetric shock wave propagates in the hydrostatic envelope and emerges from the surface. We systematically study a wide parameter space of the size of the merging neutron stars and the energy involved in the shock waves. As a result, it is found that the mass of remaining free neutrons is 10-7 to 10-6 M o, which is smaller than the previously expected mass by more than two orders of magnitude. There is a preferred energy of the order of 1048 erg that yields the maximum amount of free neutrons for large sizes of the envelope. We briefly discuss the emission from the free neutron layer and estimate the luminosity in the optical band to be about 7 ×1041 erg s ∼30 minutes after the merger.

ジャーナルAstrophysical Journal
出版ステータスPublished - 2018 7 1

ASJC Scopus subject areas

  • 天文学と天体物理学
  • 宇宙惑星科学


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