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Vintergatan - i. The origins of chemically, kinematically, and structurally distinct discs in a simulated milky way-mass galaxy

Agertz, Oscar LU ; Renaud, Florent LU ; Feltzing, Sofia LU orcid ; Read, Justin I. ; Ryde, Nils LU orcid ; Andersson, Eric P. LU ; Rey, Martin P. LU ; Bensby, Thomas LU orcid and Feuillet, Diane K. LU orcid (2021) In Monthly Notices of the Royal Astronomical Society 503(4). p.5826-5845
Abstract

Spectroscopic surveys of the Milky Way's stars have revealed spatial, chemical, and kinematical structures that encode its history. In this work, we study their origins using a cosmological zoom simulation, VINTERGATAN, of a MilkyWay-mass disc galaxy. We find that in connection to the last major merger at z ∼ 1.5, cosmological accretion leads to the rapid formation of an outer, metal-poor, low-[α/Fe] gas disc around the inner, metal-rich galaxy containing the old high-[α/Fe] stars. This event leads to a bimodality in [α/Fe] over a range of [Fe/H]. A detailed analysis of how the galaxy evolves since z ∼ 1 is presented. We demonstrate the way in which inside-out growth shapes the radial surface density and metallicity profile and how... (More)

Spectroscopic surveys of the Milky Way's stars have revealed spatial, chemical, and kinematical structures that encode its history. In this work, we study their origins using a cosmological zoom simulation, VINTERGATAN, of a MilkyWay-mass disc galaxy. We find that in connection to the last major merger at z ∼ 1.5, cosmological accretion leads to the rapid formation of an outer, metal-poor, low-[α/Fe] gas disc around the inner, metal-rich galaxy containing the old high-[α/Fe] stars. This event leads to a bimodality in [α/Fe] over a range of [Fe/H]. A detailed analysis of how the galaxy evolves since z ∼ 1 is presented. We demonstrate the way in which inside-out growth shapes the radial surface density and metallicity profile and how radial migration preferentially relocates stars from the inner disc to the outer disc. Secular disc heating is found to give rise to increasing velocity dispersions and scale heights with stellar age, which together with disc flaring explains several trends observed in the MilkyWay, including shallower radial [Fe/H] profiles above the mid-plane.We show how the galaxy formation scenario imprints non-trivial mappings between structural associations (i.e. thick and thin discs), velocity dispersions, α-enhancements, and ages of stars; e.g. the most metal-poor stars in the low-[α/Fe] sequence are found to have a scale height comparable to old high-[α/Fe] stars. Finally, we illustrate how at low spatial resolution, comparable to the thickness of the galaxy, the proposed pathway to distinct sequences in [α/Fe]-[Fe/H] cannot be captured.

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published
subject
keywords
Galaxies: Evolution, Galaxies: Formation, Galaxies: Structure, Galaxy: Abundances, Galaxy: Formation, Methods: numerical
in
Monthly Notices of the Royal Astronomical Society
volume
503
issue
4
pages
20 pages
publisher
Oxford University Press
external identifiers
  • scopus:85106226934
ISSN
0035-8711
DOI
10.1093/mnras/stab322
language
English
LU publication?
yes
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Funding Information: We thank the anonymous referee for useful comments that improved the quality of the manuscript. OA thanks Romain Teyssier, Andrea Macciò, Tobias Buck, Ted Mackereth, and Andrey Kravtsov for discussions. OA, FR, EA, and MR acknowledge support from the Knut and Alice Wallenberg Foundation and the Royal Physiographic Society of Lund. OA, FR, and EA acknowledge support from the Royal Physiographic Society of Lund. OA is supported by the grant 2014-5791 from the Swedish Research Council. TB is supported by the grant 2018-04857 from the Swedish Research Council. SF and DF are supported by the grant 2016-03412 from the Swedish Research Council. This work used the COSMA Data Centric system at Durham University, operated by the Institute for Computational Cosmology on behalf of the STFC DiRAC HPC Facility (www.dirac.ac.uk). This equipment was funded by a BIS National E-infrastructure capital grant ST/K00042X/1, DiRAC Operations grant ST/K003267/1, and Durham University. DiRAC is part of the National E-Infrastructure. Publisher Copyright: © 2021 Oxford University Press. All rights reserved.
id
cbbd30be-1706-4c43-924b-06f8f9a2a8ef
date added to LUP
2021-10-28 09:47:27
date last changed
2023-01-01 17:11:45
@article{cbbd30be-1706-4c43-924b-06f8f9a2a8ef,
  abstract     = {{<p>Spectroscopic surveys of the Milky Way's stars have revealed spatial, chemical, and kinematical structures that encode its history. In this work, we study their origins using a cosmological zoom simulation, VINTERGATAN, of a MilkyWay-mass disc galaxy. We find that in connection to the last major merger at z ∼ 1.5, cosmological accretion leads to the rapid formation of an outer, metal-poor, low-[α/Fe] gas disc around the inner, metal-rich galaxy containing the old high-[α/Fe] stars. This event leads to a bimodality in [α/Fe] over a range of [Fe/H]. A detailed analysis of how the galaxy evolves since z ∼ 1 is presented. We demonstrate the way in which inside-out growth shapes the radial surface density and metallicity profile and how radial migration preferentially relocates stars from the inner disc to the outer disc. Secular disc heating is found to give rise to increasing velocity dispersions and scale heights with stellar age, which together with disc flaring explains several trends observed in the MilkyWay, including shallower radial [Fe/H] profiles above the mid-plane.We show how the galaxy formation scenario imprints non-trivial mappings between structural associations (i.e. thick and thin discs), velocity dispersions, α-enhancements, and ages of stars; e.g. the most metal-poor stars in the low-[α/Fe] sequence are found to have a scale height comparable to old high-[α/Fe] stars. Finally, we illustrate how at low spatial resolution, comparable to the thickness of the galaxy, the proposed pathway to distinct sequences in [α/Fe]-[Fe/H] cannot be captured.</p>}},
  author       = {{Agertz, Oscar and Renaud, Florent and Feltzing, Sofia and Read, Justin I. and Ryde, Nils and Andersson, Eric P. and Rey, Martin P. and Bensby, Thomas and Feuillet, Diane K.}},
  issn         = {{0035-8711}},
  keywords     = {{Galaxies: Evolution; Galaxies: Formation; Galaxies: Structure; Galaxy: Abundances; Galaxy: Formation; Methods: numerical}},
  language     = {{eng}},
  number       = {{4}},
  pages        = {{5826--5845}},
  publisher    = {{Oxford University Press}},
  series       = {{Monthly Notices of the Royal Astronomical Society}},
  title        = {{Vintergatan - i. The origins of chemically, kinematically, and structurally distinct discs in a simulated milky way-mass galaxy}},
  url          = {{http://dx.doi.org/10.1093/mnras/stab322}},
  doi          = {{10.1093/mnras/stab322}},
  volume       = {{503}},
  year         = {{2021}},
}