Impact of the Cosmic Web on the Properties of Galaxies in IllustrisTNG Simulations

Abstract We investigate the influence of the cosmic web on galaxy properties in the IllustrisTNG simulations. To disentangle the effects of galaxy groups and cosmic filaments, we divide the cosmic web environment into four categories: group, group-dominated region, filament-dominated region, and field. By controlling for stellar mass, we reveal evident differences in specific star formation rates (sSFRs), quenched fraction, gas fractions, local density, and stellar ages among central galaxies in different cosmic web environments, particularly for lower-mass galaxies. However, these differences largely diminish when the effect of local overdensity is further accounted for, indicating its dominant role. Additionally, we observe distinct differences in these properties among satellite galaxies across environments, mainly driven by stellar mass, halo mass, and overdensity. Notably, residual differences between satellites in field and filament-dominated regions persist even after controlling for these factors, suggesting a stronger susceptibility of satellite galaxies to filaments compared to central galaxies. Our findings highlight the importance of differentiating between central and satellite to accurately assess the environmental effects of the cosmic web. Our analysis suggests that the relationship between galaxy properties and their distance from filaments arises from a combination of factors, including stellar and halo mass, groups, overdensity, and the intrinsic influence of the cosmic web. Additionally, we find that the effect of the cosmic web on galaxy properties is reduced at z = 0.5, compared to z = 0. Furthermore, central galaxies near thick filaments tend to exhibit slightly to moderately lower sSFR and cold gas fractions compared to those near thin filaments.