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

TL;DR

This study uses the MTNG hydrodynamic simulation to analyze how satellite galaxies' baryonic components and mass profiles evolve, providing insights for improving galaxy modeling in simulations.

Contribution

It offers a detailed analysis of satellite galaxy evolution, highlighting how gas and stellar components change over time and proposing proxies for simpler modeling.

Findings

Gas mass declines rapidly, losing ~80% by half-mass loss.

Stellar mass and magnitudes evolve more slowly, linked to subhalo v_max.

Mass loss occurs in outer and inner regions early on.

Abstract

Empirical models often rely on key relations from the galaxy--halo connection to construct mock galaxy catalogues. These relations typically describe central galaxies 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 use \MTNG, a state-of-the-art cosmological hydrodynamic simulation, to study the evolution of the baryonic component of satellites. Using the merger trees from this simulation, we follow the evolution of all $z=0$ satellite galaxies, tracking their stellar mass, gas mass, and $r$- and $U$-band magnitudes. We characterise this evolution using proxies including the fraction of subhalo mass and maximum circular velocity remaining 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 $\sim 80\%$ 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 overall slower and is better described by the reduction of the host subhalo $v_{\rm max}$. We then examine the evolution of satellite mass profiles. We find that, although stripping is strongest in the outer regions, the intermediate and inner parts of 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.