How does a low-mass cut-off in the stellar IMF affect the evolution of young star clusters?

TL;DR

This study examines how varying the low-mass cutoff in the stellar initial mass function influences the mass loss, expansion, and survival of young star clusters, revealing that the effects are less dramatic than expected.

Contribution

It demonstrates that different low-mass cut-offs in the IMF have limited impact on cluster destruction timescales and highlights the complex interdependence of cluster properties.

Findings

Clusters with higher-mass stars lose more mass through stellar evolution.

Clusters expand and slow their dynamical evolution after mass loss.

Changing the IMF biases towards more massive stars speeds up dissolution but not dramatically.

Abstract

We investigate how different stellar initial mass functions (IMFs) can affect the mass loss and survival of star clusters. We find that IMFs with radically different low-mass cut-offs (between 0.1 and 2 Msun) do not change cluster destruction time-scales as much as might be expected. Unsurprisingly, we find that clusters with more high-mass stars lose relatively more mass through stellar evolution, but the response to this mass loss is to expand and hence significantly slow their dynamical evolution. We also argue that it is very difficult, if not impossible, to have clusters with different IMFs that are initially "the same", since the mass, radius and relaxation times depend on each other and on the IMF in a complex way. We conclude that changing the IMF to be biased towards more massive stars does speed up mass loss and dissolution, but that it is not as dramatic as might be thought.