Linking the Internal Properties of Infant Globular Clusters to their Formation Environments

TL;DR

This study uses high-resolution cosmological simulations to explore how infant globular clusters form and evolve, revealing their environmental dependence and internal dynamics, and linking early formation processes to present-day observations.

Contribution

It provides new insights into the formation environments and internal properties of infant globular clusters, highlighting the role of external triggers and feedback mechanisms.

Findings

Infant GCs first become gravitationally bound at specific redshifts.

Radial infall of gas and stars characterizes their collapse.

Supernova feedback leads to gas loss and adiabatic expansion.

Abstract

We investigate the formation of infant globular cluster (GC) candidates in high-resolution cosmological simulations from the First Billion Years (FiBY) project. By analysing the evolution of the systems in the energy and angular momentum plane, we identify the redshift at which the infant GCs first became gravitationally bound, and we find evidence of radial infall of their gaseous and stellar components. The collapse appears to be driven by internal self-gravity, however, the initial trigger is sourced from the external environment. The phase space behaviour of the infant GCs also allows us to identify some characteristic groupings of objects. Such a classification based on internal properties appears to be reflected in the formation environment: GC candidates that belong to the same class are found in host galaxies of similar morphology, with the majority of the infant GCs located in clumpy, irregular proto-galaxies. Finally, through the inspection of two GC candidates that contain only stars by z = 6, we find that supernova feedback is the main physical mechanism behind their dearth of gas and that the systems subsequently respond with an approximately adiabatic expansion. Such infant GC candidates already resemble the GCs we currently observe in the local Universe.