Hyperonic degrees of freedom in binary neutron star mergers

TL;DR

This study investigates how hyperons affect binary neutron star mergers, revealing impacts on gravitational waves, remnant temperature, mass ejection, and black hole formation thresholds through extensive simulations.

Contribution

It provides the first comprehensive analysis of hyperonic effects on merger dynamics across multiple equations of state using large-scale simulations.

Findings

Hyperons influence the gravitational-wave spectral features.

Remnants with hyperons have lower average temperatures.

Hyperonic models show increased mass ejection and reduced black hole formation threshold.

Abstract

We analyze the influence of hyperons in binary neutron star mergers considering several different equations of state that include hyperons. By running a large set of simulations, we study the impact of the thermally produced hyperons on the gravitational-wave spectral features, the temperature evolution of the remnant, the mass ejecta and the threshold mass for prompt collapse to a black hole. Models with hyperons tend to stand out in the relation between the dominant postmerger gravitational-wave frequency and the tidal deformability of massive stars. Moreover, the averaged temperature of the remnant is reduced for hyperonic models. The mass ejection of the mergers is tentatively enhanced when hyperons are present in comparison to nucleonic EoSs leading to similar stellar properties of cold neutron stars, whereas the threshold mass for prompt black-hole formation is reduced by about 0.05~$M_\odot$ compared to the nucleonic models.