Star cluster disruption in the starburst galaxy Messier 82

TL;DR

This study analyzes the age, mass, and spatial distribution of 846 star clusters in M82 using Hubble data, revealing three distinct age groups and insights into cluster disruption and galaxy evolution.

Contribution

It provides a comprehensive, multi-band analysis of star cluster populations in M82, highlighting their age distribution, disruption history, and spatial characteristics with high-resolution data.

Findings

Three clear age peaks in cluster distribution

Massive clusters are concentrated in the galaxy's center

Intermediate-age clusters are more spatially dispersed

Abstract

Using high-resolution, multiple-passband Hubble Space Telescope images spanning the entire optical/near-infrared wavelength range, we obtained a statistically complete sample, $U$-band selected sample of 846 extended star clusters across the disk of the nearby starburst galaxy M82. Based on careful analysis of their spectral energy distributions, we determined their galaxy-wide age and mass distributions. The M82 clusters exhibit three clear peaks in their age distribution, thus defining a relatively young, log(t/yr) < 7.5, an intermediate-age, log(t/yr) $\in$ [7.5, 8.5], and an old sample, log(t/yr) > 8.5. Comparison of the completeness-corrected mass distributions offers a firm handle on the galaxy's star cluster disruption history. The most massive star clusters in the young and old samples are (almost) all concentrated in the most densely populated central region, while the intermediate-age sample's most massive clusters are more spatially dispersed, which may reflect the distribution of the highest-density gas throughout the galaxy's evolutionary history, combined with the solid-body nature of the galaxy's central region.