Auriga Streams III: the mass–metallicity relation does not rule out tidal mass-loss in Local Group satellites
Year: 2026
Type: article
Abstract: ABSTRACT The mass–metallicity relation is a fundamental galaxy scaling law that has been extended to the faintest systems in the Local Group. We show that the small scatter in this relation, which has been used to argue against tidal mass-loss in Local Group satellites, is consistent with the level of disruption in the Auriga simulations. For every accreted system in Auriga, we compute stellar masses and metallicities two ways: considering the total system (bound + lost material) and only considering the progenitor. Accreted systems in Auriga have a tight relation between total stellar mass and metallicity, with scatter at a fixed stellar mass driven by age. When only considering the progenitor, the tidally evolved mass–metallicity relation has similar scatter ($\sim$0.27 dex) as observed for the Local Group satellites ($\sim$0.23 dex). Satellites that lie above the evolved relation have experienced substantial mass-loss and typically have low metallicity for their total stellar mass. Even satellites that fall exactly on the evolved relation can lose over half of their stellar mass. Only satellites substantially below the evolved relation are reliably intact. Based on their offset from the observed relation, we predict which Milky Way and M31 satellites have tidal tails waiting to be discovered.
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,046
Funders: U.S. Department of Energy, National Aeronautics and Space Administration, Department for Business, Energy and Industrial Strategy, UK Government, Ukrainian Research Institute, Harvard University, European Commission, Durham University, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Universität Zürich, Agencia Nacional de Investigación y Desarrollo, Science and Technology Facilities Council
Awards: G102163711, G1061316111, Durham DiRAC-2 petascale facility, DiRAC-2.5 - the pathway to DiRAC Phase 3, G2121721726, G2578892563, GalaHAD: Galaxy Formation With High Accuracy Dynamics, G4452337565, DiRAC-2.5 DC - Operations 2017-2020, SCARS OF EVOLUTION: UNVEILING GALACTIC HISTORIES THROUGH MORPHOLOGICAL PERTURBATIONS AND ONGOING ACTIVITY, Towards a Self-Consistent Multi-Scale Theory of the Feedback-Cycle in Massive Galaxies, DiRAC: Memory Intensive 2.5y, Astronomy at Durham 2020-2023, DiRAC: Memory Intensive 2.5x
OpenAlex ID: W4415057174