Dynamical Capture Binary Neutron Star Mergers

TL;DR

This paper investigates dynamical capture binary neutron star mergers in dense stellar environments, analyzing outcomes like black hole formation, hypermassive neutron stars, and associated electromagnetic and gravitational signals.

Contribution

It provides new insights into how impact parameter and neutron star equation of state influence merger outcomes and ejecta in dynamical capture scenarios.

Findings

Mergers can lead to prompt black hole collapse or hypermassive neutron stars.

Ejected material can be up to a few percent of a solar mass.

Accretion disks of up to 0.1 solar masses can form.

Abstract

We study dynamical capture binary neutron star mergers as may arise in dense stellar regions such as globular clusters. Using general-relativistic hydrodynamics, we find that these mergers can result in the prompt collapse to a black hole or in the formation of a hypermassive neutron star, depending not only on the neutron star equation of state but also on impact parameter. We also find that these mergers can produce accretion disks of up to a tenth of a solar mass and unbound ejected material of up to a few percent of a solar mass. We comment on the gravitational radiation and electromagnetic transients that these sources may produce.