"The Impact of Local and Large-Scale Environment on the Stellar Populations of LEGA-C Galaxies at Intermediate Redshifts"

Abstract:
Despite the key role of the large-scale matter distribution in the Universe in regulating hierarchical structure formation, its impact on the baryonic physics that shape star formation and chemical enrichment histories of galaxies is still not fully understood. In this work, we assess the effect of local and large-scale environmental metrics on stellar population properties and star formation timescales derived from rest-frame optical absorption spectra and photometry of massive LEGA-C galaxies at 0.6<z<1. We report that overdensity derived from reconstructed density field is the main environmental metric driving the stellar population properties of massive galaxies (M_star>10^10 Msun) at intermediate redshifts. We observe that galaxies of a given stellar mass in overdense regions are older and form earlier on and over shorter time-scales than the ones in underdense regions. What’s more interesting, these trends remain after accounting for the galaxies’ hierarchy within groups and clusters and their position in the large-scale cosmic web. Our results suggest that the initial conditions of the matter density field have a profound effect on the quenching and star formation histories of galaxies, leaving an imprint into observed galaxy stellar populations and scaling relations that are already in place at intermediate redshifts.