Neutron Stars in Globular Clusters

TL;DR

This study uses numerical simulations to explore neutron star retention and binary formation in globular clusters, explaining observed X-ray binaries and pulsar populations through dynamical interactions and specific supernova mechanisms.

Contribution

It demonstrates that electron-capture supernovae are necessary to explain neutron star retention and reproduces observed correlations in globular cluster populations.

Findings

Neutron star retention requires electron-capture supernovae.

Simulations match observed LMXB dependence on collision number.

Good agreement with observed millisecond pulsar populations.

Abstract

Dynamical interactions that occur between objects in dense stellar systems are particularly important for the question of formation of X-ray binaries. We present results of numerical simulations of 70 globular clusters with different dynamical properties and a total stellar mass of 2*10^7 Msun. We find that in order to retain enough neutron stars to match observations we must assume that NSs can be formed via electron-capture supernovae. Our simulations explain the observed dependence of the number of LMXBs on ``collision number'' as well as the large scatter observed between different globular clusters. For millisecond pulsars, we obtain good agreement between our models and the numbers and characteristics of observed pulsars in the clusters Terzan 5 and 47 Tuc