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Orkney, MDA, Laporte, CFP, Grand, RJJ, Gómez, FA, van de Voort, F, Marinacci, F, Fragkoudi, F, Pakmor, R and Springel, V (2022) The impact of two massive early accretion events in a Milky Way-like galaxy: repercussions for the buildup of the stellar disc and halo. Monthly Notices of the Royal Astronomical Society: Letters, 517 (1). L138-L142. ISSN 1745-3925
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The impact of two massive early accretion events in a Milky Way-like galaxy repercussions for the buildup of the stellar disc and halo.pdf - Published Version Download (1MB) | Preview |
Abstract
We identify and characterize a Milky Way-like realization from the Auriga simulations with two consecutive massive mergers ∼2
Gyr apart at high redshift, comparable to the reported Kraken and Gaia-Sausage-Enceladus. The Kraken-like merger (z = 1.6, MTot=8×1010M⊙) is gas-rich, deposits most of its mass in the inner 10 kpc, and is largely isotropic. The Sausage-like merger (z = 1.14, MTot=1×1011M⊙) leaves a more extended mass distribution at higher energies, and has a radially anisotropic distribution. For the higher-redshift merger, the stellar mass ratio of the satellite to host galaxy is high (1:3). As a result, the chemistry of the remnant is indistinguishable from contemporaneous in situ populations, making it challenging to identify through chemical abundances. This naturally explains why all abundance patterns attributed so far to Kraken are in fact fully consistent with the metal-poor in situ so-called Aurora population and thick disc. However, our model makes a falsifiable prediction: if the Milky Way underwent a gas-rich double merger at high redshift, then this should be imprinted on its star formation history with bursts about ∼2 s apart. This may offer constraining power on the highest-redshift massive mergers.
| Item Type: | Article |
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| Additional Information: | This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society: Letters ©: 2022 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. |
| Subjects: | Q Science > QB Astronomy Q Science > QC Physics |
| Divisions: | Astrophysics Research Institute |
| Publisher: | Oxford University Press (OUP) |
| SWORD Depositor: | A Symplectic |
| Date Deposited: | 18 Apr 2023 12:32 |
| Last Modified: | 18 Apr 2023 12:32 |
| DOI or ID number: | 10.1093/mnrasl/slac126 |
| URI: | https://researchonline.ljmu.ac.uk/id/eprint/19374 |
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