Brief Comments on ``The Shapiro Conjecture, Prompt or Delayed Collapse ?'' by Miller, Suen and Tobias

TL;DR

This paper discusses numerical simulations of neutron star collisions to evaluate the Shapiro conjecture, highlighting the importance of simulation subtleties in high-mass cases and their impact on predicting collapse or stability.

Contribution

It analyzes the challenges and numerical subtleties in simulating neutron star collisions near the maximum mass, providing insights into the conjecture's validity.

Findings

Simulations show mixed results regarding the conjecture.

High-mass progenitors pose numerical challenges.

Simulation subtleties can influence collapse predictions.

Abstract

Recent numerical simulations address a conjecture by Shapiro that when two neutron stars collide head-on from rest at infinity, sufficient thermal pressure may be generated to support the hot remnant in quasi-static equilibrium against collapse prior to neutrino cooling. The conjecture is meant to apply even when the total remnant mass exceeds the maximum mass of a cold neutron star. One set of simulations seems to corroborate the conjecture, while another, involving higher mass progenitors each very close to the maximum mass, does not. In both cases the total mass of the remnant exceeds the maximum mass. We point out numerical subtleties in performing such simulations when the progenitors are near the maximum mass; they can explain why the simulations might have difficulty assessing the conjecture in such high-mass cases.