# MOCCA-SURVEY database I. Accreting white dwarf binary systems in globular clusters -- IV. cataclysmic variables -- properties of bright and faint populations

**Authors:** Diogo Belloni, Mirek Giersz, Liliana E. Rivera Sandoval, Abbas Askar, Paweł Ciecieląg  
**arXiv:** [1811.04937](https://arxiv.org/abs/1811.04937)  
**Date:** 2018-11-12  
**Summary page:** https://www.summarizepaper.com/en/paper/1811.04937v1/

## Key points

- Belloni et al. conducted a study on cataclysmic variables (CVs) in 288 globular cluster (GC) models using the MOCCA code.
- Destruction of primordial CV progenitors due to dynamical interactions within GCs is more common than the formation of new CVs through such interactions.
- Detectable CV populations in these GC models are mainly composed of CVs that have undergone a common envelope phase (CEP), accounting for over 70%.
- Only a small fraction (2-4%) of all CVs within a given GC are likely observable.
- Models with core collapse tend to host a higher proportion of bright CVs compared to non-core-collapsed models.
- Differentiation between bright and faint CV populations based on pre-CV and CV formation rates, as well as their characteristics at formation times and cluster half-mass relaxation times was introduced by Belloni et al.
- GC models adhering to an initial binary population model proposed by Kroupa and featuring low CEP efficiency offer better agreement with observed quantities of CVs in specific clusters like NGC 6397, NGC 6752, and 47 Tuc.
- Accurate identification and characterization of candidate objects as true CVs through obtaining essential parameters like orbital periods and mass ratios is crucial for advancing comparisons further.

## Summary

In this study, Belloni et al. explore the populations of cataclysmic variables (CVs) within a comprehensive set of 288 globular cluster (GC) models that have been evolved using the MOCCA code. This research represents the most extensive analysis of GC models with respect to CVs to date. The authors discover that the destruction of primordial CV progenitors due to dynamical interactions within GCs is significantly more prevalent than the formation of new CVs through such interactions. They also observe that dynamically formed CVs and those formed without strong dynamical influences exhibit similar distributions in terms of white dwarf masses. Furthermore, the study reveals that detectable CV populations in these GC models are predominantly composed of CVs that have undergone a typical common envelope phase (CEP), accounting for over 70% of the detectable population. Only a small fraction, approximately 2-4%, of all CVs within a given GC are likely to be observable. Additionally, models with core collapse tend to host a higher proportion of bright CVs compared to non-core-collapsed models. A novel aspect introduced by Belloni and colleagues is the differentiation between bright and faint CV populations based on pre-CV and CV formation rates, as well as their characteristics at formation times and cluster half-mass relaxation times. By applying these parameters, they provide insights into understanding the properties exhibited by both types of CVs. Moreover, the researchers demonstrate that GC models adhering to an initial binary population model proposed by Kroupa and featuring low CEP efficiency offer better agreement with observed quantities of CVs and potential candidates in specific clusters such as NGC 6397, NGC 6752, and 47 Tuc. To advance these comparisons further, it is crucial to accurately identify and characterize candidate objects as true CVs through obtaining essential parameters like orbital periods and mass ratios. Overall, this detailed investigation sheds light on the complex dynamics governing the formation and evolution of cataclysmic variables within globular clusters, offering valuable insights into their properties and distribution across different cluster environments.