Gas surface density, star formation rate surface density, and the maximum mass of young star clusters in a disk galaxy. I. The flocculent galaxy M33

TL;DR

This study investigates how the maximum mass of young star clusters in galaxy M33 correlates with various gas surface densities and star formation rates, revealing strong physical relationships.

Contribution

It establishes quantitative relationships between maximum cluster mass and gas/sfr surface densities, highlighting physical causes over sample size effects.

Findings

M_max ∝ Sigma_gas^4.7

M_max ∝ Sigma_H2^1.3

M_max ∝ Sigma_SFR^1.0

Abstract

We analyze the relationship between maximum cluster mass, M_max, and surface densities of total gas (Sigma_gas), molecular gas (Sigma_H2) and star formation rate (Sigma_SFR) in the flocculent galaxy M33, using published gas data and a catalog of more than 600 young star clusters in its disk. By comparing the radial distributions of gas and most massive cluster masses, we find that M_max is proportional to Sigma_gas^4.7, M_max is proportional Sigma_H2^1.3, and M_max is proportional to Sigma_SFR^1.0. We rule out that these correlations result from the size of sample; hence, the change of the maximum cluster mass must be due to physical causes.