Auriga Streams II: orbital properties of tidally disrupting satellites of Milky Way-mass galaxies

Shipp, N ORCID: 0000-0003-2497-091X, Riley, AH ORCID: 0000-0001-5805-5766, Simpson, CM ORCID: 0000-0001-9985-1814, Bieri, R ORCID: 0000-0002-4554-4488, Necib, L ORCID: 0000-0003-2806-1414, Arora, A, Fragkoudi, F ORCID: 0000-0002-0897-3013, Gómez, FA ORCID: 0000-0003-4232-8584, Grand, RJJ ORCID: 0000-0001-9667-1340 and Marinacci, F ORCID: 0000-0003-3816-7028 (2025) Auriga Streams II: orbital properties of tidally disrupting satellites of Milky Way-mass galaxies. Monthly Notices of the Royal Astronomical Society, 542 (2). pp. 1109-1124. ISSN 0035-8711

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Abstract

Galaxies like the Milky Way are surrounded by complex populations of satellites at all stages of tidal disruption. In this paper, we present a dynamical study of the disrupting satellite galaxies in the Auriga simulations that are orbiting 28 distinct Milky Way-mass hosts across three resolutions. We find that the satellite galaxy populations are highly disrupted. The majority of satellites that remain fully intact at present day were accreted recently without experiencing more than one pericentre ( nperi ≲ 1) and have large apocentres ( rapo ≳ 200kpc ) and pericentres ( rperi ≳ 50kpc ). The remaining satellites have experienced significant tidal disruption and, given full knowledge of the system, would be classified as stellar streams. We find stellar streams in Auriga across the range of pericentres and apocentres of the known Milky Way dwarf galaxy streams and, interestingly, overlapping significantly with the Milky Way intact satellite population. We find no significant change in satellite orbital distributions across resolution. However, we do see substantial halo-to-halo variance of ( rperi , rapo ) distributions across host galaxies, as well as a dependence of satellite orbits on host halo mass–systems disrupt at larger pericentres and apocentres in more massive hosts. Our results suggest that either cosmological simulations (including, but not limited to, Auriga) are disrupting satellites far too readily, or that the Milky Way’s satellites are more disrupted than current imaging surveys have revealed. Future observing facilities and careful mock observations of these systems will be key to revealing the nature of this apparent discrepancy.

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:	31 July 2025
Date of first compliant Open Access:	9 October 2025
Date Deposited:	09 Oct 2025 15:50
Last Modified:	09 Oct 2025 16:00
DOI or ID number:	10.1093/mnras/staf1283
URI:	https://researchonline.ljmu.ac.uk/id/eprint/27308

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