Stellar mass of each galaxy at redshift z = 0 for varying primordial magnetic field strength, color-coded by the virial mass of the dark matter halo. In the left panel, each circle represents one galaxy simulated in the MHD suite (ΛCDM model). In the right panel, galaxies shown as empty diamonds (ΛCDM+PMFs model) consider both magneto-hydrodynamics and the contribution of primordial fields to the matter power spectrum. The stellar mass of halos which do not form any stars is shown at M_⋆ < 10⁴ M_⊙ instead of 0 M_⊙. Halos that do not reach redshift z = 0, due to extensive CPU-hours required, are identified by marking them with an upward arrow.