On the edge: the relation between stellar and dark matter haloes of Milky Way-mass galaxies

Genina, A; Deason, AJ; Frenk, CS

Abstract

We investigate the build-up of the accreted stellar and dark matter haloes of Milky Way-like galaxies in APOSTLE suite of cosmological hydrodynamics simulations. We show that the stellar halo is made up primarily of stars stripped from a small number of massive dwarfs, most of which are disrupted by the present day. The dark matter halo, on the other hand, is made up primarily of small unresolved subhaloes (≲106 M⊙) and a ‘smooth’ component consisting of particles which were never bound to a subhalo. Despite these differences, the massive dwarfs that make up the majority of the stellar halo also contribute a significant fraction of the dark matter. The stars and dark matter stripped from these dwarfs are related through their kinematics and this leaves imprints in the phase-space structure of the haloes. We examine the relation between the location of features, such as caustics, in the phase space of the stars and dark halo properties. We show that the ‘edge’ of the stellar halo is a probe of dark matter halo mass and assembly history. The edges of Milky Way-mass galaxies should be visible at a surface brightness of 31–36 mag arcsec−2.

Citation

Genina, A., Deason, A., & Frenk, C. (2023). On the edge: the relation between stellar and dark matter haloes of Milky Way-mass galaxies. Monthly Notices of the Royal Astronomical Society, 520(3), 3767-3787. https://doi.org/10.1093/mnras/stad397

• Journal Article Type: Article
• Acceptance Date: Feb 2, 2023
• Online Publication Date: Feb 6, 2023
• Publication Date: 2023-04
• Deposit Date: May 24, 2023
• Publicly Available Date: May 24, 2023
• 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: 520
• Issue: 3
• Pages: 3767-3787
• DOI: https://doi.org/10.1093/mnras/stad397
• Public URL: https://durham-repository.worktribe.com/output/1173137