A new approach to subhalo mass modeling in cosmology simulations

The Last Journey simulation, an extreme-scale gravity-only cosmology simulation, ran on the Mira supercomputer at the Argonne Leadership Computing Facility and evolved over 1.24 trillion particles in a (5025 Mpc)$^3$ volume. We plan to add galaxies to Last Journey using a semi-analytic model; the result of this project will enable us to create detailed synthetic sky maps for cosmological surveys. To include subhalo information in galaxy modeling, we have developed a core tracking approach which is much less computationally expensive than subhalo finding. We accumulate and track cores, the central particles of halos, for all output steps. Using a downscaled simulation, we have applied a subhalo mass loss model found in literature to cores of halos that have merged into a host. We show that the mass function of the modeled cores agrees well with the mass function of subhalos identified by a subhalo finding algorithm after adjusting the model parameters, providing a powerful tool to use within semi-analytic galaxy modeling.