The Milky Way in context: The formation of galactic discs and chemical sequences from a cosmological perspective

We study the formation of chemical sequences in the stellar disc of Milky Way (MW)-mass galaxies in a full cosmological context with the auriga simulations. We focus on the conditions giving rise to bi-modal $α$-chemistry in the MW disc and the potential influence of mergers (e.g. Gaia-Enceladus, GS...

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Detalhes bibliográficos
Autores: Orkney, Matthew D. A., Laporte, Chervin F. P., Grand, Robert J. J., Springel, Volker
Formato: artículo
Estado:Versión publicada
Fecha de publicación:2026
País:España
Recursos:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/420264
Acesso em linha:http://hdl.handle.net/10261/420264
http://arxiv.org/abs/2506.07038v2
Access Level:acceso abierto
Palavra-chave:Galaxies: abundances
Galaxy: abundances
Galaxy: disc
Galaxy: evolution
Methods: numerical
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spelling The Milky Way in context: The formation of galactic discs and chemical sequences from a cosmological perspectiveOrkney, Matthew D. A.Laporte, Chervin F. P.Grand, Robert J. J.Springel, VolkerGalaxies: abundancesGalaxy: abundancesGalaxy: discGalaxy: evolutionMethods: numericalWe study the formation of chemical sequences in the stellar disc of Milky Way (MW)-mass galaxies in a full cosmological context with the auriga simulations. We focus on the conditions giving rise to bi-modal $α$-chemistry in the MW disc and the potential influence of mergers (e.g. Gaia-Enceladus, GSE). We find a wide diversity of chemical sequences, without correlation between the emergence of dichotomous $α$-chemistry and GSE-like mergers. The transition between multiple $α$-sequences is sequential, and is mediated by modulations in the star formation rate (SFR). In some cases, this can be caused by the starburst and subsequent quiescence induced by mergers. In others, by exhaustion or violent disruption of the gas disc. Realisations with singular sequences either lack significant modulations in their SFR, or form too late to have a significant high-$α$ sequence. The metallicity overlap between the high-$α$ and low-$α$ sequences (as seen in the Solar neighbourhood of the MW) arises from accretion of metal-poor gas from the circum-galactic medium. This depends on gas disc thickness, with thinner discs losing their metal-poor extremities. Gas donation from singular gas-rich merger events are incapable of driving long-lived metal dilution ($Δ\text{[Fe/H]} \gtrsim 0.3$), and we rule-out this scenario for the low-$α$ sequence in the MW. Finally, the shape of $α$-sequences in the [Fe/H] versus [Mg/Fe] plane is related to long-term SFR trends, with a downward slanted locus (as is observed in the low-$α$ sequence of the MW) owing to a sustained or declining SFR.We thank the anonymous referee for their thoughtful comments, which have greatly contributed to this manuscript. This work has used resources from the MareNostrum 4 supercomputer at the Barcelona Supercomputing Center (BSC). Much of our analysis was performed on the Virgo supercomputer at the Max Planck Computing and Data Facility (MPCDF). Further analysis and simulation work was performed on the NYX supercomputer at the Universität de Barcelona (ICCUB). CL and MO acknowledge funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 852839). CL also acknowledges funding from the Agence Nationale de la Recherche (ANR projectANR-24-CPJ1-0160-01). RJJG is supported by an STFC Ernest Rutherford Fellowship (ST/W003643/1).Peer reviewedOxford University PressEuropean Research CouncilAgence Nationale de la Recherche (France)European CommissionUK Research and InnovationOrkney, Matthew D. A. [0000-0002-8151-8498]Laporte, Chervin F. P. [0000-0003-3922-7336]Grand, Robert J. J. [0000-0001-9667-1340]Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]202620262026info:eu-repo/semantics/articlehttp://purl.org/coar/resource_type/c_6501Publisher's versioninfo:eu-repo/semantics/publishedVersionapplication/pdfhttp://hdl.handle.net/10261/420264http://arxiv.org/abs/2506.07038v2reponame:DIGITAL.CSIC. Repositorio Institucional del CSICinstname:Consejo Superior de Investigaciones Científicas (CSIC)Inglés#PLACEHOLDER_PARENT_METADATA_VALUE#info:eu-repo/grantAgreement/EC/H2020/852839The underlying dataset has been published as supplementary material of the article in the publisher platform at DOI 10.1093/mnras/staf1551https://doi.org/10.1093/mnras/staf1551Síinfo:eu-repo/semantics/openAccessoai:digital.csic.es:10261/4202642026-05-22T06:33:51Z
dc.title.none.fl_str_mv The Milky Way in context: The formation of galactic discs and chemical sequences from a cosmological perspective
title The Milky Way in context: The formation of galactic discs and chemical sequences from a cosmological perspective
spellingShingle The Milky Way in context: The formation of galactic discs and chemical sequences from a cosmological perspective
Orkney, Matthew D. A.
Galaxies: abundances
Galaxy: abundances
Galaxy: disc
Galaxy: evolution
Methods: numerical
title_short The Milky Way in context: The formation of galactic discs and chemical sequences from a cosmological perspective
title_full The Milky Way in context: The formation of galactic discs and chemical sequences from a cosmological perspective
title_fullStr The Milky Way in context: The formation of galactic discs and chemical sequences from a cosmological perspective
title_full_unstemmed The Milky Way in context: The formation of galactic discs and chemical sequences from a cosmological perspective
title_sort The Milky Way in context: The formation of galactic discs and chemical sequences from a cosmological perspective
dc.creator.none.fl_str_mv Orkney, Matthew D. A.
Laporte, Chervin F. P.
Grand, Robert J. J.
Springel, Volker
author Orkney, Matthew D. A.
author_facet Orkney, Matthew D. A.
Laporte, Chervin F. P.
Grand, Robert J. J.
Springel, Volker
author_role author
author2 Laporte, Chervin F. P.
Grand, Robert J. J.
Springel, Volker
author2_role author
author
author
dc.contributor.none.fl_str_mv European Research Council
Agence Nationale de la Recherche (France)
European Commission
UK Research and Innovation
Orkney, Matthew D. A. [0000-0002-8151-8498]
Laporte, Chervin F. P. [0000-0003-3922-7336]
Grand, Robert J. J. [0000-0001-9667-1340]
Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]
dc.subject.none.fl_str_mv Galaxies: abundances
Galaxy: abundances
Galaxy: disc
Galaxy: evolution
Methods: numerical
topic Galaxies: abundances
Galaxy: abundances
Galaxy: disc
Galaxy: evolution
Methods: numerical
description We study the formation of chemical sequences in the stellar disc of Milky Way (MW)-mass galaxies in a full cosmological context with the auriga simulations. We focus on the conditions giving rise to bi-modal $α$-chemistry in the MW disc and the potential influence of mergers (e.g. Gaia-Enceladus, GSE). We find a wide diversity of chemical sequences, without correlation between the emergence of dichotomous $α$-chemistry and GSE-like mergers. The transition between multiple $α$-sequences is sequential, and is mediated by modulations in the star formation rate (SFR). In some cases, this can be caused by the starburst and subsequent quiescence induced by mergers. In others, by exhaustion or violent disruption of the gas disc. Realisations with singular sequences either lack significant modulations in their SFR, or form too late to have a significant high-$α$ sequence. The metallicity overlap between the high-$α$ and low-$α$ sequences (as seen in the Solar neighbourhood of the MW) arises from accretion of metal-poor gas from the circum-galactic medium. This depends on gas disc thickness, with thinner discs losing their metal-poor extremities. Gas donation from singular gas-rich merger events are incapable of driving long-lived metal dilution ($Δ\text{[Fe/H]} \gtrsim 0.3$), and we rule-out this scenario for the low-$α$ sequence in the MW. Finally, the shape of $α$-sequences in the [Fe/H] versus [Mg/Fe] plane is related to long-term SFR trends, with a downward slanted locus (as is observed in the low-$α$ sequence of the MW) owing to a sustained or declining SFR.
publishDate 2026
dc.date.none.fl_str_mv 2026
2026
2026
dc.type.none.fl_str_mv info:eu-repo/semantics/article
http://purl.org/coar/resource_type/c_6501
Publisher's version
info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/10261/420264
http://arxiv.org/abs/2506.07038v2
url http://hdl.handle.net/10261/420264
http://arxiv.org/abs/2506.07038v2
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv #PLACEHOLDER_PARENT_METADATA_VALUE#
info:eu-repo/grantAgreement/EC/H2020/852839
The underlying dataset has been published as supplementary material of the article in the publisher platform at DOI 10.1093/mnras/staf1551
https://doi.org/10.1093/mnras/staf1551
Sí
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv Oxford University Press
publisher.none.fl_str_mv Oxford University Press
dc.source.none.fl_str_mv reponame:DIGITAL.CSIC. Repositorio Institucional del CSIC
instname:Consejo Superior de Investigaciones Científicas (CSIC)
instname_str Consejo Superior de Investigaciones Científicas (CSIC)
reponame_str DIGITAL.CSIC. Repositorio Institucional del CSIC
collection DIGITAL.CSIC. Repositorio Institucional del CSIC
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15.812429

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