The ACS Nearby Galaxy Survey Treasury. X. Quantifying the Star Cluster Formation Efficiency of Nearby Dwarf Galaxies

TL;DR

This study investigates how star and cluster formation relate in nearby dwarf galaxies, revealing that stochastic sampling explains some variability but not all, indicating true differences in star cluster formation efficiency.

Contribution

It provides the first constraints on the relationship between galaxy star formation rates and cluster properties in low SFR regimes, highlighting real variations in cluster formation efficiency.

Findings

Broad agreement with proposed SFR-cluster property relationships

Significant galaxy-to-galaxy scatter not fully explained by stochastic sampling

Constraints on cluster destruction models from brightest cluster analysis

Abstract

We study the relationship between the field star formation and cluster formation properties in a large sample of nearby dwarf galaxies. We use optical data from the Hubble Space Telescope and from ground-based telescopes to derive the ages and masses of the young (t_age < 100Myr) cluster sample. Our data provides the first constraints on two proposed relationships between the star formation rate of galaxies and the properties of their cluster systems in the low star formation rate regime. The data show broad agreement with these relationships, but significant galaxy-to-galaxy scatter exists. In part, this scatter can be accounted for by simulating the small number of clusters detected from stochastically sampling the cluster mass function. However, this stochasticity does not fully account for the observed scatter in our data suggesting there may be true variations in the fraction of stars formed in clusters in dwarf galaxies. Comparison of the cluster formation and the brightest cluster in our sample galaxies also provide constraints on cluster destruction models.