Eccentric binary neutron star mergers

TL;DR

This paper presents the first numerical relativity study of eccentric equal-mass neutron-star mergers, revealing gravitational wave signals with stellar oscillation components and the formation of massive accretion disks.

Contribution

It introduces a novel investigation of eccentric neutron-star mergers, bridging the gap between head-on collisions and circular orbits in relativistic simulations.

Findings

Detection of strong stellar oscillation (f-modes) in gravitational wave signals

Formation of massive disks (~10% of total mass) post-merger

Eccentric mergers produce distinct gravitational wave features

Abstract

Neutron star binaries offer a rich phenomenology in terms of gravitational waves and merger remnants. However, most general relativistic studies have been performed for nearly circular binaries, with the exception of head-on collisions. We present the first numerical relativity investigation of mergers of eccentric equal-mass neutron-star binaries that probes the regime between head-on and circular. In addition to gravitational waves generated by the orbital motion, we find that the signal also contains a strong component due to stellar oscillations (f-modes) induced by tidal forces, extending a classical result for Newtonian binaries. The merger can lead to rather massive disks on the order of 10% of the total initial mass.