The dynamics of star-forming regions - which mechanisms set the cluster formation efficiency?

TL;DR

This paper reviews the mechanisms influencing the cluster formation efficiency (CFE) in star-forming regions, emphasizing recent advancements in understanding environmental impacts beyond gas expulsion, and highlights future research directions.

Contribution

It discusses recent progress in disentangling various mechanisms affecting CFE and outlines the necessary studies for a quantitative understanding.

Findings

CFE is influenced by multiple mechanisms beyond gas expulsion.

Recent advancements help distinguish environmental effects on CFE.

Future studies are needed for a quantitative model of CFE.

Abstract

The fraction of star formation that results in bound stellar clusters (cluster formation efficiency or CFE) is a central quantity in many studies of star formation, star clusters and galaxies. Recent results suggest that contrary to popular assumption, the CFE is not (solely) set by gas expulsion, but is also influenced by the primordial environment, although its precise behaviour remains unknown. Here it is discussed which mechanisms set the CFE, which recent advancements have been made to disentangle their contributions, and which studies are needed in the near future to achieve a quantitative understanding of the CFE.