Description
The evolution of galaxies is thought to be connected to their cosmic web environment. While environment is typically quantified using observed galaxy catalogues (e.g. using DisPerSE), this approach suffers from survey incompleteness and the uncertain relationship between visible galaxies and the dark matter backbone of the cosmic web.
Here we present the results of arxiv:2503.14732, where we use the CSiBORG suite of constrained simulations, designed to reproduce the actual large scale structure of the local Universe, to instead quantify environment using the underlying dark matter density field at the positions of observed galaxies. We define environment using both cosmic web position, identified by applying DisPerSE to the constrained simulation halos, and the local dark matter density (averaged on scales of up to 16 Mpc/h). We correlate these environmental measures with observed galaxy properties from optical (NASA-Sloan Atlas) and radio (ALFALFA) surveys. We robustly quantify statistical significance by exploiting both the Bayesian nature of the BORG algorithm, and using a supporting suite of unconstrained simulations.
We find significant correlations between environment and galaxy properties. Bluer, star-forming, HI-rich disk galaxies predominantly occupy lower density regions farther from filaments, while redder, elliptical galaxies with reduced star formation rates exist in higher density areas closer to filaments. Galaxy quenching shows similar patterns, with low-mass galaxy quenching demonstrating stronger environmental dependence than high-mass counterparts.
Notably, galaxy properties correlate more strongly with environmental density than with distance to filaments, suggesting local density exerts greater influence on galaxy characteristics than positioning within the larger cosmic web structure.
