The Cluster Birthline and the formation of stellar clusters in M33

TL;DR

This paper introduces a new method to analyze the high-mass end of the initial mass function in young stellar clusters using bolometric and Halpha luminosities, showing a stochastic universal IMF fits M33 data better than a truncated one.

Contribution

It presents a novel approach to study the IMF in stellar clusters and compares stochastic versus truncated IMF models using observational data from M33.

Findings

A stochastic universal IMF aligns better with observations than a truncated IMF.

Evidence suggests possible delayed formation of massive stars in low-density regions.

The method provides insights into star formation processes in M33.

Abstract

We present a new method to analyze the IMF at its high mass end in young stellar clusters, which rely on two integrated observables: the cluster bolometric and Halpha luminosity. Using several cluster samples selected in M33 we show that a stochastically sampled universal IMF is in better agreement with the data than a truncated IMF whose maximum stellar mass depends on cluster mass. We also discuss the possibility that a delayed formation of massive stars is taking place in low density star forming regions as an alternative to a strong leakage of ionizing photons from HII regions of young luminous clusters.