Head-on/Near Head-on Collisions of Neutron Stars With a Realistic EOS

TL;DR

This paper challenges previous beliefs by showing that neutron star mergers with realistic equations of state can undergo prompt collapse even if their total mass is below the maximum stable mass, through simulations of head-on collisions.

Contribution

It introduces the Prompt Collapse Conjecture, demonstrating that prompt collapse can occur below the maximum stable mass in head-on neutron star collisions with realistic EOS.

Findings

Prompt collapse can occur below the maximum stable mass.

Simulations confirm the Prompt Collapse Conjecture.

Collapse occurs in both head-on and near head-on collisions.

Abstract

It has been conjectured that in head-on collisions of neutron stars (NSs), the merged object would not collapse promptly even if the total mass is higher than the maximum stable mass of a cold NS. In this paper, we show that the reverse is true: even if the total mass is {\it less} than the maximum stable mass, the merged object can collapse promptly. We demonstrate this for the case of NSs with a realistic equation of state (the Lattimer-Swesty EOS) in head-on {\it and} near head-on collisions. We propose a ``Prompt Collapse Conjecture'' for a generic NS EOS for head on and near head-on collisions.