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

Orkney, MDA, Laporte, CFP, Grand, RJJ ORCID: 0000-0001-9667-1340, Gómez, FA, Van De Voort, F, Fattahi, A, Marinacci, F, Pakmor, R, Fragkoudi, F and Springel, V (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). pp. 683-705. ISSN 0035-8711

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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 () and include both rotation and pressure-supported galaxies (0.10 < D/T < 0.77) In a minority of cases, the GSE-like debris is comprised of stars from more than one merger progenitor However, there is a close similarity in their chemodynamical properties and the triaxial shapes of their debris, and so it is not always possible to distinguish them The merger progenitors host a variety of luminous satellites (0 and 8 with), 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] â-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
Uncontrolled Keywords:	methods: numerical; Galaxy: abundances; Galaxy: centre; Galaxy: evolution; Galaxy: kinematics and dynamics; Galaxy: structure; 5109 Space Sciences; 5101 Astronomical Sciences; 51 Physical Sciences; 5109 Space Sciences; 5101 Astronomical Sciences; 51 Physical Sciences; 0201 Astronomical and Space Sciences; Astronomy & Astrophysics; 5101 Astronomical sciences; 5107 Particle and high energy physics; 5109 Space sciences
Subjects:	Q Science > QB Astronomy
Divisions:	Astrophysics Research Institute
Publisher:	Oxford University Press (OUP)
Date of acceptance:	28 July 2023
Date of first compliant Open Access:	6 January 2026
Date Deposited:	06 Jan 2026 12:15
Last Modified:	06 Jan 2026 12:15
DOI or ID number:	10.1093/mnras/stad2361
URI:	https://researchonline.ljmu.ac.uk/id/eprint/27819

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