Rey, Martin P;
Agertz, Oscar;
Starkenburg, Tjitske K;
Renaud, Florent;
Joshi, Gandhali D;
Pontzen, Andrew;
Martin, Nicolas F;
... Read, Justin I; + view all
(2023)
VINTERGATAN-GM: The cosmological imprints of early mergers on Milky-Way-mass galaxies.
Monthly Notices of the Royal Astronomical Society
, 521
(1)
pp. 995-1012.
10.1093/mnras/stad513.
Preview |
Text
stad513.pdf - Published Version Download (3MB) | Preview |
Abstract
We present a new suite of cosmological zoom-in hydrodynamical ($\approx 20\, \mathrm{pc}$ spatial resolution) simulations of Milky-Way mass galaxies to study how a varying mass ratio for a Gaia-Sausage-Enceladus (GSE) progenitor impacts the z = 0 chemodynamics of halo stars. Using the genetic modification approach, we create five cosmological histories for a Milky-Way-mass dark matter halo ($M_{200}\approx 10^{12} \, \mbox{M}_\mathrm{\odot }$), incrementally increasing the stellar mass ratio of a z ≈ 2 merger from 1:25 to 1:2, while fixing the galaxy’s final dynamical, stellar mass, and large-scale environment. We find markedly different morphologies at z = 0 following this change in early history, with a growing merger resulting in increasingly compact and bulge-dominated galaxies. Despite this structural diversity, all galaxies show a radially biased population of inner halo stars like the Milky-Way’s GSE which, surprisingly, has a similar magnitude, age, $\rm [Fe/H]$, and $\rm [\alpha /Fe]$ distribution whether the z ≈ 2 merger is more minor or major. This arises because a smaller ex-situ population at z ≈ 2 is compensated by a larger population formed in an earlier merger-driven starburst whose contribution to the GES can grow dynamically over time, and with both populations strongly overlapping in the $\rm [Fe/H]-\rm [\alpha /Fe]$ plane. Our study demonstrates that multiple high-redshift histories can lead to similar z = 0 chemodynamical features in the halo, highlighting the need for additional constraints to distinguish them, and the importance of considering the full spectrum of progenitors when interpreting z = 0 data to reconstruct our Galaxy’s past.
| Type: | Article |
|---|---|
| Title: | VINTERGATAN-GM: The cosmological imprints of early mergers on Milky-Way-mass galaxies |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/stad513 |
| Publisher version: | https://doi.org/10.1093/mnras/stad513 |
| Language: | English |
| Additional information: | © 2023 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. |
| Keywords: | methods: numerical, Galaxy: formation, Galaxy: halo, galaxies: formation, galaxies: kinematics and dynamics |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10168351 |
Archive Staff Only
 |
View Item |
