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Exploring the diversity and similarity of radially anisotropic Milky Way-like stellar haloes: Implications for disrupted dwarf galaxy searches

Orkney, Matthew D. A., Laporte, Chervin F. P., Grand, Robert J. J., Gómez, Facundo A., van de Voort, Freeke ORCID: https://orcid.org/0000-0002-6301-638X, Fattahi, Azadeh, Marinacci, Federico, Pakmor, Rüdiger, Fragkoudi, Francesca and Springel, Volker 2023. Exploring the diversity and similarity of radially anisotropic Milky Way-like stellar haloes: Implications for disrupted dwarf galaxy searches. Monthly Notices of the Royal Astronomical Society 525 (1) 10.1093/mnras/stad2361

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Abstract

We investigate the properties of mergers comparable to the Gaia–Sausage–Enceladus (GSE) using cosmological hydrodynamical simulations of Milky Way-like galaxies. The merger progenitors span an order of magnitude in their peak stellar mass (⁠3×108106M⊙ ⁠), but most of these do not follow the merger to low orbital energies. Between 0 and 1 of these satellites may survive to z = 0, but with no clear signatures of their past association. We show that the fraction of stars originating from GSE-like mergers is reduced for lower metallicities (reaching a minimum around [Fe/H] = −2), and also within 5 kpc of the Galactic Centre. Whilst these central regions are dominated by in-situ stars, the ex-situ fraction trends towards a 100 per cent asymptote when considering the most metal-poor stars ([Fe/H] ≪ −2.5). Considering this, its near proximity, and its small volume on the sky, the Galactic Centre lends itself as a prime environment in the search for the stars from the earliest galaxies, whilst avoiding contamination from GSE stars.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Physics and Astronomy
Publisher: Oxford University Press
ISSN: 0035-8711
Date of First Compliant Deposit: 20 October 2023
Date of Acceptance: 28 July 2023
Last Modified: 06 Nov 2023 13:25
URI: https://orca.cardiff.ac.uk/id/eprint/163347

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