"Investigating the Effects of SMBH Feedback on Galaxy Morphology using FIRE-2 Simulations"

In the local universe, low-mass irregular galaxies (stellar mass ~ 10^9 M_sun) and Milky Way mass disk galaxies (stellar mass ~ 10^10 M_sun) are typically star-forming, while massive, elliptical galaxies (stellar mass ~ 10^11 M_sun) are usually “quenched” or not forming stars. Simulations have shown that supermassive black hole (SMBH) feedback shuts down star formation in these massive galaxies and is required to reproduce the observed galaxy population at low redshift. The details of how SMBH Feedback corresponds to galaxy morphology are still not fully understood. To elucidate the effects of SMBH Feedback on galaxy morphology, we analyze a subset of 9 Milky Way-mass galaxies with live SMBH feedback from the Feedback In Realistic Environments (FIRE) simulations. Using circularity (epsilon = J_z/J_c(E)) as a proxy for morphology, we investigate how the presence of SMBH feedback energetics, like heating and outflows/winds, disrupts star formation and the subsequent morphological evolution of galaxies over cosmic time. We find that SMBH feedback reduces star formation across three evolutionary phases corresponding to spheroidal, thick disk, and thin disk morphologies. The effect of SMBH during the disk formation phase results in more spheroidal-shaped galaxies under SMBH Feedback than without.