Research Division Seminar
Galaxy stellar populations illuminating dark matter halo evolution

Abstract

The coupling between the baryonic cycle of galaxies and dark matter halo assembly is central to our understanding of galaxies, and yet, it remains a challenge for theoretical models and elusive to observations. In this talk, I report observational evidence demonstrating that different baryonic properties of nearby galaxies are controlled by their host halos. We map galaxy ages, metallicities and star formation histories across the stellar-to-halo mass relation for SDSS central galaxies using absorption optical spectra. In addition to stellar populations, we also investigate the stellar angular momentum, star formation rates and galaxy morphology across the stellar-to-total dynamical mass relation for CALIFA galaxies. We find that the scatter of both relations correlates with these galaxy properties, which are determined by the combined role of stellar and halo/total mass. Galaxies become older, more metal-rich and less rotationally supported, form the bulk of their stars earlier on and faster, have lower star formation rates and earlier-type morphologies as their stellar mass increases (at fixed halo/total mass). Furthermore, we also observe that the scatter of the star-forming main sequence is driven by galaxies that have experienced different evolutionary histories. We interpret our results as being driven by halo evolution, with galaxies/halos at different evolutionary stages modulating the variety of galaxy properties observed at fixed stellar mass. Our findings call for a revision of the sub-grid physics implementation in cosmological numerical simulations, in particular during the early stages of galaxy formation, and warn observational studies to account for the profound effect that halo formation time may have on measured galaxy properties.

Zoom Link: https://rediris.zoom.us/j/96210828127?pwd=Z25JdFg1bnpRTVBSQUdpTVlwUDgyQT09