  Halo core tracking is a novel concept designed to efficiently follow halo
substructure in large simulations. We have recently developed this concept in
gravity-only simulations to investigate the galaxy-halo connection in the
context of empirical and semi-analytic models. Here, we incorporate information
from hydrodynamics simulations, with an emphasis on establishing a connection
between cores and galaxies. We compare cores across gravity-only, adiabatic
hydrodynamics, and subgrid hydrodynamics simulations with the same initial
phases. We demonstrate that cores are stable entities whose halo-centric radial
profiles match across the simulations. We further develop a methodology that
uses merging and infall mass cuts to group cores in the hydrodynamics
simulation, creating on average, a one-to-one match to corresponding galaxies.
We apply this methodology to cores from the gravity-only simulation, thus
creating a proxy for galaxies which approximate the populations from the
hydrodynamics simulation. Our results pave the way to incorporate inputs from
smaller-scale hydrodynamics simulations directly into large-scale gravity-only
runs in a principled manner.
