The tidal evolution of satellite galaxies in cosmological simulations: insights from COLIBRE

TL;DR

This study uses COLIBRE cosmological simulations to analyze the tidal evolution of satellite galaxies, revealing a universal mass loss pattern, the formation of dark-matter-deficient galaxies, and the impact of numerical effects.

Contribution

It introduces a two-phase model of tidal mass loss, predicts conditions for dark-matter-deficient galaxies, and assesses numerical effects on satellite galaxy properties.

Findings

Universal tidal track links stellar and dark matter mass loss.

Dark-matter-deficient galaxies peak at stellar mass ~10^9.5 M_sun.

Artificial disruption can bias stellar mass functions by up to 50%."

Abstract

We investigate the co-evolution of the stellar and dark matter mass of satellite galaxies using the COLIBRE cosmological hydrodynamical simulations with subhaloes resolved by the history-based HBT-HERONS subhalo finder. We identify a universal tidal track connecting stellar mass loss to subhalo mass loss characterized by two distinct phases, which can be well described by the two-parameter model. The initial phase consists primarily of dark matter stripping, whereas stellar stripping becomes significant only after the subhalo bound mass fraction drops below a critical value ($\sim 0.057$). We find a bimodal mass loss rate distribution of subhaloes. In satellites with modest mass loss rates, the stellar mass is largely frozen. By contrast, the galaxy quickly becomes unresolved, along with the dark matter component for the extreme-mass-loss population, naturally explaining the lack of ``orphan'' galaxies in previous hydrodynamical simulations. Our model also predicts the formation condition for dark-matter-deficient galaxies (DMDGs), whose abundance peaks at $m_{*}\sim 10^{9.5}\,\rm{M}_{\odot}$. The abundance of DMDGs can be very sensitive to numerical effects, with COLIBRE resolving a much larger DMDG population than previous hydrodynamical simulations. We also estimate the influence of artificial disruption on the satellite stellar mass function, which can amount to 20 (50) per cent at $m_* \sim 10^{9} (10^{8}) \, \rm M_\odot$, given a baryonic mass resolution of $\sim 10^{6}\,\rm{M}_{\odot}$.