The giants that were born swiftly -- Implications of the top-heavy stellar initial mass function on the birth conditions of globular clusters

TL;DR

This study explores how a top-heavy stellar initial mass function influences the initial mass and supernova activity in globular clusters, suggesting more massive clusters formed closer to galactic centers and slightly shortening star formation duration.

Contribution

It demonstrates that a metallicity and density-dependent IMF leads to larger initial masses and more supernovae in globular clusters than previously estimated with a canonical IMF.

Findings

IMFs of GCs are top-heavy, implying larger initial masses.

More core collapse supernovae are needed to explain iron spreads.

Massive GCs likely formed closer to galactic centers.

Abstract

Recent results suggest that the initial mass function (IMF) of globular clusters (GCs) is metallicity and density dependent. Here it is studied how this variation affects the initial masses and the numbers of core collapse supernovae (CCSNe) required to reproduce the observed iron spreads in GCs. The IMFs of all of the investigated GCs were top-heavy implying larger initial masses compared to previous results computed assuming an invariant canonical IMF. This leads to more CCSNe being required to explain the observed iron abundance spreads. The results imply that the more massive GCs formed at smaller Galactocentric radii, possibly suggesting in-situ formation of the population II halo. The time until star formation (SF) ended within a proto-GC is computed to be 3.5 - 4 Myr, being slightly shorter than the 4 Myr obtained using the canonical IMF. Therefore, the impact of the IMF on the time for which SF lasts is small.