Formation of Compact Stellar Clusters by High-Redshift Galaxy Outflows III: Observability and Connection to Halo Globular Clusters

TL;DR

This study uses simulations to show that high-redshift galaxy outflows can transform minihalos into dense, chemically homogeneous stellar clusters, which may be observed as halo globular clusters today.

Contribution

The paper demonstrates through extensive simulations that galaxy outflows at high redshift can create stellar clusters resembling present-day halo globular clusters, linking early universe processes to observed structures.

Findings

Minihalos are transformed into dense stellar clusters by outflows.

Simulated clusters are chemically homogeneous and compact.

Clusters are observable with next-generation telescopes.

Abstract

The early universe hosted a large population of low-mass virialized "minihalos," that were not massive enough to form stars on their own. While most minihalos were photoevaporated by ionizing photons from star-forming galaxies, these galaxies also drove large outflows, which in some cases would have reached the minihalos in advance of ionization fronts. In the previous papers in this series, we carried out high-resolution, three-dimensional adaptive mesh refinement simulations of outflow-minihalo interactions that included non-equilibrium chemistry, radiative cooling, and turbulent mixing. We found that, for a fiducial set of parameters, minihalos were transformed into dense, chemically homogenous stellar clusters. Here we conduct a suite of simulations that follow these interactions over a wide range of parameters including minihalo mass, minihalo formation redshift, outflow energy, outflow redshift, distance, concentration, and spin. In almost all cases, the shocked minihalos form molecules through nonequillibrium reactions and then cool rapidly to become compact, chemically-homogenous stellar clusters. Furthermore, we show that the unique properties of these clusters make them a prime target for direct study with the next generation of telescopes, and that there are many reasons to suspect that their low-redshift counterparts are the observed population of halo globular clusters.