Skip to main content

Research Repository

Advanced Search

The origin of galactic metal-rich stellar halo components with highly eccentric orbits

Fattahi, Azadeh; Belokurov, Vasily; Deason, Alis J; Frenk, Carlos S; Gómez, Facundo A; Grand, Robert JJ; Marinacci, Federico; Pakmor, Rüdiger; Springel, Volker

The origin of galactic metal-rich stellar halo components with highly eccentric orbits Thumbnail


Authors

Vasily Belokurov

Facundo A Gómez

Robert JJ Grand

Federico Marinacci

Rüdiger Pakmor

Volker Springel



Abstract

Using the astrometry from the ESA’s Gaia mission, previous works have shown that the Milky Way stellar halo is dominated by metal-rich stars on highly eccentric orbits. To shed light on the nature of this prominent halo component, we have analysed 28 Galaxy analogues in the Auriga suite of cosmological hydrodynamics zoom-in simulations. Some three quarters of the Auriga galaxies contain prominent components with high radial velocity anisotropy, β > 0.6. However, only in one third of the hosts do the high-β stars contribute significantly to the accreted stellar halo overall, similar to what is observed in the Milky Way. For this particular subset we reveal the origin of the dominant stellar halo component with high metallicity, [Fe/H]∼−1, and high orbital anisotropy, β > 0.8, by tracing their stars back to the epoch of accretion. It appears that, typically, these stars come from a single dwarf galaxy with a stellar mass of order of 109 − 1010 M⊙ that merged around 6 − 10 Gyr ago, causing a sharp increase in the halo mass. Our study therefore establishes a firm link between the excess of radially anisotropic stellar debris in the halo and an ancient head-on collision between the young Milky Way and a massive dwarf galaxy.

Citation

Fattahi, A., Belokurov, V., Deason, A. J., Frenk, C. S., Gómez, F. A., Grand, R. J., …Springel, V. (2019). The origin of galactic metal-rich stellar halo components with highly eccentric orbits. Monthly Notices of the Royal Astronomical Society, 484(4), 4471-4483. https://doi.org/10.1093/mnras/stz159

Journal Article Type Article
Acceptance Date Jan 14, 2019
Online Publication Date Jan 16, 2019
Publication Date Apr 21, 2019
Deposit Date Feb 6, 2019
Publicly Available Date Mar 29, 2024
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 484
Issue 4
Pages 4471-4483
DOI https://doi.org/10.1093/mnras/stz159

Files

Accepted Journal Article (620 Kb)
PDF

Copyright Statement
© 2019 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.






You might also like



Downloadable Citations