How to Find Young Massive Cluster Progenitors

TL;DR

This paper proposes a model where bound young massive clusters form from dense clouds with high escape speeds, enabling star formation to proceed efficiently despite radiative feedback, and discusses how to observe these proto-clusters.

Contribution

It introduces a new criterion based on escape speed to identify progenitors of young massive clusters and suggests observational strategies to find them.

Findings

Dense clouds with escape speeds > sound speed form bound clusters.

Radiative feedback is trapped in high escape speed clouds, allowing high star formation efficiency.

Potential observable properties of proto-clusters are estimated for Galactic and extragalactic surveys.

Abstract

We propose that bound, young massive stellar clusters form from dense clouds that have escape speeds greater than the sound speed in photo-ionized gas. In these clumps, radiative feedback in the form of gas ionization is bottled up, enabling star formation to proceed to sufficiently high efficiency so that the resulting star cluster remains bound even after gas removal. We estimate the observable properties of the massive proto-clusters (MPCs) for existing Galactic plane surveys and suggest how they may be sought in recent and upcoming extragalactic observations. These surveys will potentially provide a significant sample of MPC candidates that will allow us to better understand extreme star-formation and massive cluster formation in the Local Universe.