The young star cluster population of M51 with LEGUS - II. Testing environmental dependencies

TL;DR

This study investigates how young star cluster properties in galaxy M51 vary with environment, revealing consistent mass function shapes but differing disruption rates and age distributions across regions.

Contribution

It provides a detailed analysis of environmental dependencies of young star clusters in M51 using LEGUS data, highlighting variations in mass function slopes and disruption rates.

Findings

Mass function has a power-law slope close to -2 with an exponential cutoff around 10^5 M_sun.

Inter-arm regions have steeper mass function slopes than arm regions.

Disruption rates are higher in dense, inner regions of the galaxy.

Abstract

It has recently been established that the properties of young star clusters (YSCs) can vary as a function of the galactic environment in which they are found. We use the cluster catalogue produced by the Legacy Extragalactic UV Survey (LEGUS) collaboration to investigate cluster properties in the spiral galaxy M51. We analyse the cluster population as a function of galactocentric distance and in arm and inter-arm regions. The cluster mass function exhibits a similar shape at all radial bins, described by a power law with a slope close to $-2$ and an exponential truncation around $10^5\ \rm{M}_{\odot}$ . While the mass functions of the YSCs in the spiral arm and inter-arm regions have similar truncation masses, the inter-arm region mass function has a significantly steeper slope than the one in the arm region; a trend that is also observed in the giant molecular cloud mass function and predicted by simulations. The age distribution of clusters is dependent on the region considered, and is consistent with rapid disruption only in dense regions, while little disruption is observed at large galactocentric distances and in the inter-arm region. The fraction of stars forming in clusters does not show radial variations, despite the drop in the $H_2$ surface density measured as function of galactocentric distance. We suggest that the higher disruption rate observed in the inner part of the galaxy is likely at the origin of the observed flat cluster formation efficiency radial profile.