Simulations agree: the Milky Way's satellites are disrupting
Abstract
Recent analyses of simulated Milky Way-mass galaxies have highlighted the prevalence of satellites undergoing tidal disruption. However, these have focused on single hydrodynamical codes with a number of limitations, making it unclear how generic this result is. We compare satellite disruption in four models: two cosmological hydrodynamical simulations (Auriga and FIRE), cosmological N-body simulations with stellar particle tagging (Aquarius), and a semi-analytic model with varying host disk properties (SatGen). For all systems, we compute the fraction of stellar mass retained by the progenitor (fbound) at the present day. We find a remarkable agreement between FIRE, Aquarius, and SatGen; all predict that ∼20 to 30 per cent of classical-mass satellites have fbound < 0.9 (∼5 to 10 per cent have fbound < 0.5). Satellites in Auriga experience substantially more mass loss than other simulations, which we attribute to their massive central galaxies and large satellite sizes prior to infall. In the ultra-faint regime captured by Aquarius and SatGen, disruption rates are comparable to or exceeding those for classical satellites. The ubiquity of mass loss across models presents both an exciting opportunity (a plethora of stellar streams awaiting discovery) and a nuisance (for theorists using satellite counts to constrain dark matter).
Related
- ARRAKIHS: The observability of tidally stripped satellites in a Milky Way-like halo
- The tidal features of the classical Milky Way satellites: Expected in MOND but inconsistent with cold dark matter models
- An Energetic Consistency Test for Feedback-Driven Gas Loss in Milky Way Dwarf Satellites
- The missing ultra-faint satellites of the Milky Way
- The Merian Survey: A Statistical Census of Bright Satellites of Sub-Milky Way-Mass Galaxies
BibTeX
@misc{riley2026simulations,
title = {{Simulations agree: the Milky Way's satellites are disrupting}},
author = {Alexander H. Riley and Nora Shipp and J. Sebastian Monzon and Arpit Arora and Adriana Dropulic and Gray Thoron and Oscar Agertz and Santi Roca-Fàbrega},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.37328},
eprint = {2610.37328},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.37328},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Simulations agree: the Milky Way's satellites are disrupting
AU - Alexander H. Riley
AU - Nora Shipp
AU - J. Sebastian Monzon
AU - Arpit Arora
AU - Adriana Dropulic
AU - Gray Thoron
AU - Oscar Agertz
AU - Santi Roca-Fàbrega
PY - 2026
DA - 2026/10/27
PB - arXiv
DO - 10.48550/arxiv.2610.37328
UR - https://arxiv.org/abs/2610.37328
AB - Recent analyses of simulated Milky Way-mass galaxies have highlighted the prevalence of satellites undergoing tidal disruption. However, these have focused on single hydrodynamical codes with a number of limitations, making it unclear how generic this result is. We compare satellite disruption in four models: two cosmological hydrodynamical simulations (Auriga and FIRE), cosmological N-body simulations with stellar particle tagging (Aquarius), and a semi-analytic model with varying host disk properties (SatGen). For all systems, we compute the fraction of stellar mass retained by the progenitor (f_bound) at the present day. We find a remarkable agreement between FIRE, Aquarius, and SatGen; all predict that ∼20 to 30 per cent of classical-mass satellites have f_bound < 0.9 (∼5 to 10 per cent have f_bound < 0.5). Satellites in Auriga experience substantially more mass loss than other simulations, which we attribute to their massive central galaxies and large satellite sizes prior to infall. In the ultra-faint regime captured by Aquarius and SatGen, disruption rates are comparable to or exceeding those for classical satellites. The ubiquity of mass loss across models presents both an exciting opportunity (a plethora of stellar streams awaiting discovery) and a nuisance (for theorists using satellite counts to constrain dark matter).
ER -