The evolution of the baryonic content and mass profiles of satellite galaxies in MTNG simulations

¹ Facultad de Física, Universidad de Sevilla, Campus de Reina Mercedes, Av. Reina Mercedes s/n, 41012, Seville, Spain
² Donostia International Physics Center, Manuel Lardizabal Ibilbidea, 4, 20018, Donostia, Gipuzkoa, Spain
³ IKERBASQUE, Basque Foundation for Science, 48013, Bilbao, Spain
⁴ INFN – Istituto Nazionale di Fisica Nucleare, Sezione di Bologna, 40127, Bologna, Italy
⁵ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, United Kingdom
⁶ Kavli Institute for Cosmology Cambridge, Madingley Road, Cambridge, CB3 0HA, UK
⁷ Institute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham, DH1 3LE, UK
⁸ Harvard-Smithsonian Center for Astrophysics, 60 Garden St, Cambridge, MA, 02138, USA
⁹ Max Planck Institute for Astrophysics, Karl-Schwarzschild-Str. 1, D-85748, Garching, Germany

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 28 April 2026
Accepted: 5 June 2026

Abstract

Empirical models often rely on key relations from the galaxy–halo connection to construct mock galaxy catalogues. These relations typically describe central galaxies (i.e. the main galaxy of a halo) more accurately than satellite galaxies, which are generally less massive and orbit within larger haloes. Satellite galaxies are affected by a variety of physical processes that pose significant challenges for modelling. In this work, we used MTNG, a state-of-the-art cosmological hydrodynamic simulation, to study the evolution of the baryonic component of satellite galaxies. Using the merger trees from this simulation, we followed the evolution of all z = 0 satellite galaxies, tracking their stellar mass, gas mass, and r- and U-band magnitudes. We characterised this evolution using proxies including the fraction of subhalo mass and the remaining maximum circular velocity relative to infall, the pericentric distance, and the time since infall. All of these quantities are commonly available in gravity-only simulations and can therefore be used to model these trends in simpler galaxy population models. We find that the gas mass, which is well described by the remaining subhalo mass fraction, declines much more rapidly than the other components, with satellites losing ∼80% of their gas by the time the subhalo has lost half of its total mass. By contrast, the evolution of stellar mass and magnitudes is slower overall and is better described by the reduction of the satellite subhalo maximum circular velocity, v_max. We additionally provide an analytical model for the evolution of these properties. We then examine the evolution of the satellite mass profiles. We find that, although stripping is strongest in the outer regions, the intermediate and inner parts of the satellites experience mass loss at early times. The results of this work can be used by empirical models and galaxy formation models built on gravity-only simulations to improve their descriptions of satellite galaxies.