Chemical signature of gas-rich disc-disc mergers at high redshift

TL;DR

This study uses numerical simulations to identify a distinct chemical signature in galaxies formed from gas-rich disc mergers, highlighting differences in stellar populations and their chemical compositions.

Contribution

It demonstrates that gas-rich disc mergers leave a unique chemical imprint, especially in [alpha/Fe] ratios, which can be used to identify merger histories in galaxy evolution.

Findings

Thick discs formed during mergers have high [alpha/Fe] at all metallicities.

Thin discs formed later show lower [alpha/Fe] ratios.

Chemical signatures depend on merger orbital parameters.

Abstract

We performed numerical simulations of mergers between gas-rich disc galaxies, which result in the formation of late-type galaxies. Stars formed during the merger end up in a thick disc that is partially supported by velocity dispersion and has high [alpha/Fe] ratios at all metallicities. Stars formed later end up in a thin, rotationally supported disc which has lower [alpha/Fe] ratios. While the structural and kinematical properties of the merger remnants depend strongly upon the orbital parameters of the mergers, we find a clear chemical signature of gas-rich mergers.