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

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 total 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 $\sim 10^{6}\, \rm {M}_{\odot }$.