The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here: https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Profile picture Diane Feuillet

Diane Feuillet

Researcher

Profile picture Diane Feuillet

VINTERGATAN-GM : The cosmological imprints of early mergers on Milky-Way-mass galaxies

Author

  • Martin P. Rey
  • Oscar Agertz
  • Tjitske K. Starkenburg
  • Florent Renaud
  • Gandhali D. Joshi
  • Andrew Pontzen
  • Nicolas F. Martin
  • Diane K. Feuillet
  • Justin I. Read

Summary, in English

We present a new suite of cosmological zoom-in hydrodynamical (≈ 20 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 (M200 ≈ 1012 M☉), 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, [Fe/H], and [α/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 [Fe/H] − [α/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.

Department/s

  • Astrophysics
  • eSSENCE: The e-Science Collaboration

Publishing year

2023

Language

English

Pages

995-1012

Publication/Series

Monthly Notices of the Royal Astronomical Society

Volume

521

Issue

1

Document type

Journal article

Publisher

Oxford University Press

Topic

  • Astronomy, Astrophysics and Cosmology

Keywords

  • galaxies: formation
  • galaxies: kinematics and dynamics
  • Galaxy: formation
  • Galaxy: halo
  • methods: numerical

Status

Published

ISBN/ISSN/Other

  • ISSN: 0035-8711