Booms and Busts: the Burstiness of Star Formation in Nearby Dwarf Galaxies

TL;DR

This review discusses the significance of starburst events in the evolution of nearby dwarf galaxies, emphasizing the distinction between impactful systemic bursts and less significant stochastic bursts based on recent observational and theoretical studies.

Contribution

It synthesizes recent observational and synthetic studies to differentiate between systemic and stochastic starbursts and assesses their roles in galaxy evolution.

Findings

IC 10 is likely a stochastic burst galaxy, not fundamentally different from other dwarf irregulars.

Starburst frequency and impact can be inferred from stellar population studies in the Local Group.

Systemic bursts have a more profound influence on galaxy evolution than stochastic bursts.

Abstract

In this review I summarise recent advances in our understanding of the importance of starburst events to the evolutionary histories of nearby galaxies. Ongoing bursts are easily diagnosed in emission-line surveys, but assessing the timing and intensity of fossil bursts requires more effort, usually demanding color-magnitude diagrams or spectroscopy of individual stars. For ages older than ~1 Gyr, this type of observation is currently limited to the Local Group and its immediate surroundings. However, if the Local Volume is representative of the Universe as a whole, then studies of the age and metallicity distributions of star clusters and resolved stellar populations should give statistical clues as to the frequency and importance of bursts to the histories of galaxies in general. Based on starburst statistics in the literature and synthetic colour-magnitude diagram studies of Local Group galaxies, I attempt to distinguish between systemic starbursts that strongly impact galaxy evolution and stochastic bursts that can appear impressive but are ultimately of little significance on gigayear timescales. As a specific case, it appears as though IC 10, the only starburst galaxy in the Local Group, falls into the latter category and is not fundamentally different from other nearby dwarf irregular galaxies.