Effects of hyperons in binary neutron star mergers

TL;DR

This paper presents the first full general relativity simulations of binary neutron star mergers incorporating hyperonic matter, revealing hyperons' significant impact on post-merger dynamics, black hole formation, and gravitational wave signals.

Contribution

It introduces the first simulations including hyperons in neutron star mergers with neutrino cooling, highlighting hyperons' effects on gravitational wave signatures.

Findings

Hyperons influence post-merger evolution and black hole formation.

Hyperons leave detectable imprints on gravitational wave signals.

Hyperons affect the formation of accretion tori around black holes.

Abstract

Numerical simulations for the merger of binary neutron stars are performed in full general relativity incorporating both nucleonic and hyperonic finite-temperature equations of state (EOS) and neutrino cooling for the first time. It is found that even for the hyperonic EOS, a hypermassive neutron star is first formed after the merger for the typical total mass $\approx$ 2.7M\bigodot, and subsequently collapses to a black hole (BH). It is shown that hyperons play a substantial role in the post-merger dynamics, torus formation around the BH, and emission of gravitational waves (GWs). In particular, the existence of hyperons is imprinted in GWs. Therefore, GW observations will provide a potential opportunity to explore the composition of the neutron star matter.