Astronomy Tea Talk

Cosmic voids—the largest, most underdense, and least studied regions of the universe—offer a unique laboratory to study delayed and potentially pristine modes of galaxy evolution. In the local universe, void galaxies are known to be bluer, less metal-enriched, and show signs of stunted growth due to a lack of major mergers, which enables population-level tests of (i) whether burstiness is driven primarily by mergers or by internal processes, (ii) how star-formation efficiency and chemical enrichment depend on local large-scale density, and (iii) how the triggering of the AGN phenomenon varies across the cosmic web. Using the TNG300 simulation, I identify cosmic voids and void galaxies across cosmic time. Relative to non-void galaxies at all redshifts, these void galaxies are bluer, smaller, more actively star forming, more massive, and less metal enriched, while at z>1 the contrasts weaken, likely due to resolution and selection effects. I also find that void galaxies have a substantially higher fraction of active galactic nuclei. In parallel, I identify voids and void galaxies in the 24 deg^2 Spitzer/HETDEX Exploratory Large-Area (SHELA) survey out to z=0.5 by building a volume-limited catalog from Hyper Suprime-Cam and HETDEX data. I then present a preliminary analysis that uses the stellar population synthesis code Prospector to attain posteriors on star formation histories, dust, and AGN components for void galaxies in the 16-band SHELA catalog, where I present preliminary trends with redshift and void-centric distance.