Auriga Streams – I: disrupting satellites surrounding Milky Way-mass haloes at multiple resolutions

Riley, AH, Shipp, N, Simpson, CM, Bieri, R, Fattahi, A, Brown, ST, Oman, KA, Fragkoudi, F, Gómez, FA, Grand, RJJ ORCID: 0000-0001-9667-1340 and Marinacci, F (2025) Auriga Streams – I: disrupting satellites surrounding Milky Way-mass haloes at multiple resolutions. Monthly Notices of the Royal Astronomical Society, 542 (3). pp. 2443-2463. ISSN 0035-8711

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Abstract

In a hierarchically formed Universe, galaxies accrete smaller systems that tidally disrupt as they evolve in the host’s potential. We present a complete catalogue of disrupting galaxies accreted onto Milky Way-mass haloes from the Auriga suite of cosmological magnetohydrodynamic zoom-in simulations. We classify accretion events as intact satellites, stellar streams, or phase-mixed systems based on automated criteria calibrated to a visually classified sample, and match accretions to their counterparts in haloes re-simulated at higher resolution. Most satellites at the present day have lost substantial amounts of stellar mass – 67 per cent have fbound < 0.97 (our threshold of lost stellar mass to no longer be considered intact), while 53 per cent satisfy a more stringent fbound < 0.8. Streams typically outnumber intact systems, contribute a smaller fraction of overall accreted stars, and are substantial contributors at intermediate distances from the host centre (∼0.1 to ∼ 0.7R200m, or ∼35 to ∼250 kpc for the Milky Way). We also identify accretion events that disrupt to form streams around massive intact satellites instead of the main host. Streams are more likely than intact or phase-mixed systems to have experienced pre-processing, suggesting this mechanism is important for setting disruption rates around Milky Way-mass haloes. All of these results are preserved across different simulation resolutions, though we do find some hints that satellites disrupt more readily at lower resolution. The Auriga haloes suggest that disrupting satellites surrounding Milky Way-mass galaxies are the norm and that a wealth of tidal features waits to be uncovered in upcoming surveys.

Item Type:	Article
Uncontrolled Keywords:	5109 Space 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 Q Science > QC Physics
Divisions:	Astrophysics Research Institute
Publisher:	Oxford University Press
Date of acceptance:	12 August 2025
Date of first compliant Open Access:	9 October 2025
Date Deposited:	09 Oct 2025 15:39
Last Modified:	09 Oct 2025 15:45
DOI or ID number:	10.1093/mnras/staf1350
URI:	https://researchonline.ljmu.ac.uk/id/eprint/27307

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