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Cited by 1,020Stellar, planetary, and galactic studiesGalaxies: Formation, Evolution, PhenomenaAstrophysical Phenomena and Observations

Co-formation of the disc and the stellar halo★

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Belokurov, V, Erkal, D, Evans, N W, Koposov, S E, Deason, A J·2018·Monthly Notices of the Royal Astronomical Society
DOI 10.1093/mnras/sty982
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Abstract

Using a large sample of main sequence stars with 7D measurements supplied by Gaia and SDSS, we study the kinematic properties of the local (within ∼10 kpc from the Sun) stellar halo. We demonstrate that the halo’s velocity ellipsoid evolves strongly with metallicity. At the low-[Fe/H] end, the orbital anisotropy (the amount of motion in the radial direction compared with the tangential one) is mildly radial, with 0.2 <β< 0.4. For stars with [Fe/H] > −1.7, however, we measure extreme values of β∼ 0.9. Across the metallicity range considered, namely−3 < [Fe/H] < −1, the stellar halo’s spin is minimal, at the level of |$20\lt \bar{v}_{\theta }(\mathrm{kms}^{-1}) \lt 30$|⁠. Using a suite of cosmological zoom-in simulations of halo formation, we deduce that the observed acute anisotropy is inconsistent with the continuous accretion of dwarf satellites. Instead, we argue, the stellar debris in the inner halo was deposited in a major accretion event by a satellite with Mvir > 1010M⊙ around the epoch of the Galactic disc formation, between 8 and 11 Gyr ago. The radical halo anisotropy is the result of the dramatic radialization of the massive progenitor’s orbit, amplified by the action of the growing disc.

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Crossref · 10.1093/mnras/sty982

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94 of 94 references verified0 citation errors · 0 not checkable

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  • The next most massive satellite brought in a large number of GCs, many of which were formerly associated with the Canis Major 'mirage', and was dubbed Gaia-Enceladus.

    “The next most massive satellite brought in a large number of GCs, many of which were formerly associated with the Canis Major 'mirage'”

    From Kraken reveals itself – the merger history of the Milky Way reconstructed with the E-MOSAICS simulations (2020) · cites this paper as Belokurov et al. 2018

    The Discussion and Conclusions (page unavailable) describe a massive satellite accretion and speculate that its core may survive as a globular cluster. They do not say it was the next most massive satellite, that it brought in many globular clusters, or that those clusters were formerly associated with the Canis Major ‘mirage’; nor do they name the satellite Gaia-Enceladus. (LLM, conf=0.75)

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  • Belokurov et al. (2018) estimate Gaia-Enceladus was accreted 8-11 Gyr ago.

    “Belokurov et al. (2018) estimate a range of 8 11 Gyr ago”

    From Kraken reveals itself – the merger history of the Milky Way reconstructed with the E-MOSAICS simulations (2020) · cites this paper as Belokurov et al. (2018)

    The Discussion and Conclusions place the paper’s hypothesized major accretion event 8–11 Gyr ago. But the passage frames that timing conditionally rather than as a firm estimate, and our copy does not identify the event as Gaia-Enceladus. (LLM, conf=0.85)

    Experimental — accuracy not yet measured

  • Our predicted accretion redshifts largely satisfy the constraints obtained through independent methods.

    “Relative to other measurements in the literature, our predicted accretion redshifts largely satisfy the constraints obtained through independent methods.”

    From Kraken reveals itself – the merger history of the Milky Way reconstructed with the E-MOSAICS simulations (2020) · cites this paper as Belokurov et al. (2018)

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Research works printed but not linked: 2

  1. Posti L., Helmi A., Veljanoski J., Breddels M., 2017, preprint (arXiv:1711 .04766)
  2. Wyse R. F. G., 2001, in Funes J. G., Corsini E. M., eds, ASP Conf. Ser. Vol. 230, Galaxy Disks and Disk Galaxies. Astron. Soc. Pac., San Francisco, p.

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Authors
Belokurov, V, Erkal, D., Evans, N. W., Koposov, S. E., & Deason, A. J.
Affiliations
  • Flatiron Institute (US)
  • University of Surrey (GB)
  • Institute of Astronomy, Madingley Road, Cambridge CB3 0HA
  • Carnegie Mellon University (US)
  • Durham University (GB)
Corresponding author
Belokurov, V
ORCID
Venue
Monthly Notices of the Royal Astronomical Society
Publisher
Oxford University Press (OUP)
Published
2018-06-02
Volume
478
Issue
1
Pages
611-619
ISSN
  • 0035-8711 (ISSN-L)
  • 1365-2966
DOI
10.1093/mnras/sty982
OpenAlex
W2785892561
Cited by
1,020
References
94
Citations by year
2026: 90 · 2025: 154 · 2024: 133 · 2023: 142 · 2022: 140 · 2021: 146 · 2020: 114 · 2019: 83 · 2018: 18
FWCI
48.70
Type
journal article
Language
en
Open access
Licence
academic.oup.com/journals/pages/about_us/legal/notices (vor, 2 d)
Locations
  • Monthly Notices of the Royal Astronomical Society (publishedVersion)
  • Durham Research Online (Durham University) (acceptedVersion)
  • arXiv (Cornell University) (submittedVersion)
  • Edinburgh Research Explorer (University of Edinburgh) (submittedVersion, other-oa)
  • Surrey Research Insight Open Access (The University of Surrey) (submittedVersion)
  • Durham Research Online (Durham University) (submittedVersion, cc-by)
  • arXiv (Cornell University)
Funders
  • European Union’s Seventh Framework Programme (FP/2007-2013)
  • ERC (308024)
  • STFC (ST/P000451/1)
Topics
  • Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Stellar, planetary, and galactic studies
  • Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Galaxies: Formation, Evolution, Phenomena
  • Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Astrophysical Phenomena and Observations
Keywords
stellar halo, velocity ellipsoid, orbital anisotropy, metallicity dependence, major mergers, halo kinematics, zoom-in cosmological simulations

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