Double white dwarf binary population in MOCCA star clusters -- Comparisons with observations of close and wide binaries

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Autori principali: Hellström, Lucas, Giersz, Mirosław, Hypki, Arkadiusz, Belloni, Diogo, Askar, Abbas, Wiktorowicz, Grzegorz
Natura: Preprint
Pubblicazione: 2024
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author Hellström, Lucas
Giersz, Mirosław
Hypki, Arkadiusz
Belloni, Diogo
Askar, Abbas
Wiktorowicz, Grzegorz
author_facet Hellström, Lucas
Giersz, Mirosław
Hypki, Arkadiusz
Belloni, Diogo
Askar, Abbas
Wiktorowicz, Grzegorz
contents There could be a significant population of double white dwarf binaries (DWDs) inside globular clusters (GCs), however, these are often too faint to be individually observed. We have utilized a large number GC models evolved with the Monte Carlo Cluster Simulator (MOCCA) code, to create a large statistical dataset of DWDs. These models include multiple-stellar populations, resulting in two distinct initial populations: one dense and another less dense. Due to the lower density of one population, a large number of objects escape during the early GC evolution, leading to a high mass-loss rate. In this dataset we have analysed three main groups of DWDs, namely in-cluster binaries, escaped binaries, and isolated evolution of primordial binaries. We compared the properties of these groups to observations of close and wide binaries. We find that the number of escaping DWDs is significantly larger than the number of in-cluster binaries and those that form via the isolated evolution of all promiridial binaries in our GC models. This suggests that dynamics play an important role in the formation of DWDs. For close binaries, we found a good agreement in the separations of escaped binaries and isolated binaries, but in-cluster binaries showed slight differences. We could not reproduce the observed extremely low mass WDs due to the limitations of our stellar and binary evolution prescriptions. For wide binaries, we also found a good agreement in the separations and masses, after accounting for observational selection effects. We conclude that, even though the current observational samples of DWDs are extremely biased and incomplete, our results compare reasonably well with observations.
format Preprint
id arxiv_https___arxiv_org_abs_2405_04314
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Double white dwarf binary population in MOCCA star clusters -- Comparisons with observations of close and wide binaries
Hellström, Lucas
Giersz, Mirosław
Hypki, Arkadiusz
Belloni, Diogo
Askar, Abbas
Wiktorowicz, Grzegorz
Solar and Stellar Astrophysics
Astrophysics of Galaxies
There could be a significant population of double white dwarf binaries (DWDs) inside globular clusters (GCs), however, these are often too faint to be individually observed. We have utilized a large number GC models evolved with the Monte Carlo Cluster Simulator (MOCCA) code, to create a large statistical dataset of DWDs. These models include multiple-stellar populations, resulting in two distinct initial populations: one dense and another less dense. Due to the lower density of one population, a large number of objects escape during the early GC evolution, leading to a high mass-loss rate. In this dataset we have analysed three main groups of DWDs, namely in-cluster binaries, escaped binaries, and isolated evolution of primordial binaries. We compared the properties of these groups to observations of close and wide binaries. We find that the number of escaping DWDs is significantly larger than the number of in-cluster binaries and those that form via the isolated evolution of all promiridial binaries in our GC models. This suggests that dynamics play an important role in the formation of DWDs. For close binaries, we found a good agreement in the separations of escaped binaries and isolated binaries, but in-cluster binaries showed slight differences. We could not reproduce the observed extremely low mass WDs due to the limitations of our stellar and binary evolution prescriptions. For wide binaries, we also found a good agreement in the separations and masses, after accounting for observational selection effects. We conclude that, even though the current observational samples of DWDs are extremely biased and incomplete, our results compare reasonably well with observations.
title Double white dwarf binary population in MOCCA star clusters -- Comparisons with observations of close and wide binaries
topic Solar and Stellar Astrophysics
Astrophysics of Galaxies
url https://arxiv.org/abs/2405.04314