The Lowest Metallicity Stars in the LMC: Clues from MaGICC Simulations

TL;DR

This study uses cosmological simulations to explore the distribution of the earliest low-metallicity stars in a galaxy similar to the LMC, revealing their formation sites and spatial distribution.

Contribution

It provides new insights into the spatial distribution and origins of the lowest metallicity stars in LMC-like galaxies through detailed simulation analysis.

Findings

Primordial stars form in both the main galaxy and sub-halos.

Lowest metallicity stars are found at large galactocentric distances (~40kpc).

Early stars in the central galaxy remain in the inner regions throughout the simulation.

Abstract

Using a cosmological hydrodynamical simulation of a galaxy of similar mass to the Large Magellanic Cloud (LMC), we examine the predicted characteristics of its lowest metallicity populations. In particular, we emphasise the spatial distributions of first (Pop III) and second (polluted by only immediate Pop III ancestors) generation stars. We find that primordial composition stars form not only in the central galaxy's progenitor, but also in locally collapsed sub-halos during the early phases of galaxy formation. The lowest metallicity stars in these sub-halos end up in a relatively extended distribution around the host, with these accreted stars possessing present-day galactocentric distances as great as ~40kpc. By contrast, the earliest stars formed within the central galaxy remain in the inner region, where the vast majority of star formation occurs, for the entirety of the simulation. Consequently, the fraction of stars that are from the earliest generation increases strongly with radius.