Investigating the impact of stellar feedback algorithms on galactic evolution

Abstract

The numerical algorithm used to implement stellar feedback in a galactic simulation will strongly influence the resulting disk. Using two disks from the MUGS2 simulation suite (Keller et al., 2015), we study the morphologies of the disks at z = 0, the evolution of baryons and dark matter from z = 4 onward, and the accretion of gas onto the disk. Each disk is evolved with three different feedback algorithms: no feedback (NF), blastwave (BW), and superbubble (SB). We find that below a virial mass of 10[superscript 12]M[subscript circled dot], SB feedback produces a denser, colder disk; prevents the formation of, or destroys, a bulge; removes the central velocity peak in the rotation curve, in good agreement with observed rotation curves; and, maintains a core in the central dark matter density profile. Above this virial mass, the binding energy of the halo is dominant, and the differences between disks evolved with BW and SB are less evident. Furthermore, we find that SB feedback fuels a cold gas reservoir in the halo. When the disk mass surpasses ~ 4 X 10[superscript 10]M[subscript circled dot], this cold gas reservoir begins to be accreted. Thus SB disks show higher accretion rates at 0.17R[subscript vir] of ~ 2 - 4M[subscript circled dot]yr[superscript -1]. Again, these values are consistent with the observed accretion onto disk galaxies.