Dynamical Formation of Cataclysmic Variables in Globular Clusters

TL;DR

This paper uses Monte-Carlo simulations to explore how internal cluster dynamics influence the formation of cataclysmic variables in globular clusters, explaining observed correlations with stellar encounter rates.

Contribution

It demonstrates a clear link between cluster dynamics and CV formation, highlighting the role of exchange encounters and primordial binaries in this process.

Findings

Simulation results match observed N_cv and Gamma correlation.

CVs are more centrally concentrated than similar-mass single stars.

Exchange encounters produce more massive CVs absent in non-exchange formed CVs.

Abstract

The formation and evolution of X-ray sources in globular clusters is likely to be affected by the cluster internal dynamics and the stellar interactions in the cluster dense environment.Several observational studies have revealed a correlation between the number of X-ray sources and the stellar encounter rate and provided evidence of the role of dynamics in the formation of X-ray binaries. We have performed a survey of Monte-Carlo simulations aimed at exploring the connection between the dynamics and formation of cataclysmic variables (CVs) and the origin of the observed correlation between the number of these objects, $N_{\rm cv}$, and the stellar encounter rate, $\Gamma$.The results of our simulations show a correlation between $N_{\rm cv}$ and $\Gamma$ as found in observational data, illustrate the essential role played by dynamics, and shed light on the dynamical history behind this correlation. CVs in our simulations are more centrally concentrated than single stars with masses close to those of turn-off stars, although this trend is stronger for CVs formed from primordial binaries undergoing exchange encounters, which include a population of more massive CVs absent in the group of CVs formed from binaries not suffering any component exchange.