Baryonic imprints on DM haloes: the concentration-mass relation in the C AMELS simulations

The physics of baryons in haloes, and their subsequent influence on the total matter phase space, has a rich phenomenology and must be well understood in order to pursue a vast set of questions in both cosmology and astrophysics. We use the Cosmology and Astrophysics with MachinE Learning Simulation (CAMELS) suite to quantify the impact of four different galaxy formation parameters/processes (as well as two cosmological parameters) on the concentration-mass relation, c_vir-M_vir. We construct a simulation-informed non-linear model for concentration as a function of halo mass, redshift, and six cosmological/astrophysical parameters. This is done for two galaxy formation models, ILLUSTRISTNG and SIMBA, using 1000 simulations of each. We extract the imprints of galaxy formation across a wide range in mass $M_{\rm vir}\in [10^{11}, 10^{14.5}] \, {\rm M}_\odot \, h^{-1}$ and in redshift z ∈ [0, 6] finding many strong mass- and redshift-dependent features. Comparisons between the ILLUSTRISTNG and SIMBA results show the astrophysical model choices cause significant differences in the mass and redshift dependence of these baryon imprints. Finally, we use existing observational measurements of c_vir-M_vir to provide rough limits on the four astrophysical parameters. Our non-linear model is made publicly available and can be used to include CAMELS-based baryon imprints in any halo model-based analysis.