The young stellar clusters in M51 and the impact of GMC encounters

Timmi G. Jørgensen; Ross P. Church

doi:10.1093/mnras/staf1548

paper

The young stellar clusters in M51 and the impact of GMC encounters

arXiv:2509.17846 · doi:10.1093/mnras/staf1548

Abstract

We investigate the young stellar cluster population of M51 and how it is affected by encounters with giant molecular clouds (GMCs). We combine a galactic model with $N$ -body simulations of 5000 unique clusters in the mass range [600 - 24000] $M_{⊙}$ . We simulate each cluster twice: with ( $C_{R}$ ) and without ( $C_{N}$ ) tidal perturbations from the GMCs. We are able to reproduce the majority of the observed mass- and age functions. However, for the age function we see a large discrepancy for clusters with masses $\sim$ 5000 $M_{⊙}$ , which is likely related to incompleteness in the observations. We find that old low-mass clusters, located close to the galactic centre, are most likely to be disrupted. The effect of GMC encounters causes a decrease in survivability by 8 per cent points for the oldest clusters with initial masses below 6000 $M_{⊙}$ . For 15 clusters we find that the presence of GMCs can protect the $C_{R}$ clusters from the rest of the galactic tidal field and thereby cause them to retain a significantly higher fraction of stars compared to the $C N$ clusters. For clusters that are super-virialized we find that the $C_{R}$ clusters have a higher virial ratio compared to the $C_{N}$ clusters, which is a result of interactions with GMCs. We see no significant difference between the $C_{R}$ and $C_{N}$ populations, indicating that over a time period of 200 Myr the effect of the GMCs cannot be detected.

19 pages, 18 figures

The young stellar clusters in M51 and the impact of GMC encounters

Abstract

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