Johnny Powell (Reed College)
A Solution to the Missing Satellite Problem
This talk is a condensed and ChaNGa-code-centric version of the Assembling Galaxies of Resolved Anatomy (AGORA) project satellite paper by Jung. M., et al. [Jung, M., et al., ApJ, 964, 123 (2024)], The satellite paper, in turn, is based on the AGORA project paper III [Roca-F`abrega, S., et al., ApJ, 917, 64 (2021)], which was a set of zoom-in simulations by six coordinated teams of computational astrophysicists: a few SPH codes and a few mesh codes. At the heart of the satellite paper is the use of the dark matter (DM) halo finder program Rockstar. Additionally, the simulations in paper III were extended at great computational cost to an approximate redshift z of 2. The missing satellite problem, [Klypin, A., et al., ApJ, 522, 82 (1999)] was the existence of many more simulated small DM halos associated with a Milky-Way-size galaxy than observed satellites. The implementation of baryonic physics, e. g. hydrodynamics, cooling, star formation, and supernova feedback across all AGORA codes to sufficient resolution is source of the solution to the missing satellite problem. Monthly meetings of all the code leaders for paper III has insured that many idiosyncratic code issues related to baryonic physics were resolved in that publication. Additionally, these zoom meetings meant that each of the four calibrations steps required for paper III reached consensus before proceeding. In conclusion, this talk will give an overview of the entire process that has solved this much touted satellite problem.