# The origin of metal-poor and metal-rich globular clusters in E-MOSAICS

## TL;DR

This study uses cosmological simulations to explain why metal-poor globular clusters are older and more extended than metal-rich ones, attributing these differences to early formation and hierarchical galaxy assembly.

## Contribution

It demonstrates that the age and spatial distribution differences are due to early formation in the context of hierarchical galaxy assembly, using self-consistent cosmological simulations.

## Key findings

- Metal-poor GCs are older and more extended.
- Metallicity alone is not a reliable tracer of accretion.
- Cluster formation at high redshift explains observed properties.

## Abstract

It has been a long-standing open question why observed globular cluster (GC) populations of different metallicities differ in their ages and spatial distributions, with metal-poor GCs being the older and radially more extended of the two. We use the suite of 25 Milky Way-mass cosmological zoom-in simulations from the E-MOSAICS project, which self-consistently model the formation and evolution of stellar clusters and their host galaxies, to understand the properties of observed GC populations. We find that the different ages and spatial distributions of metal-poor and metal-rich GCs are the result of regular cluster formation at high redshift in the context of hierarchical galaxy assembly. We also find that metallicity on its own is not a good tracer of accretion, and other properties, such as kinematics, need to be considered.