The effect of cosmic web filaments on the properties of groups and their central galaxies

Abstract

Context. The nature versus nurture scenario in galaxy and group evolution is a long-standing problem not yet fully understood on cosmological scales. Aims. We study the properties of groups and their central galaxies in different large-scale environments defined by the luminosity density field and the cosmic web filaments. Methods. We use the luminosity density field constructed using 8 h −1 Mpc smoothing to characterize the large-scale environments. We use the Bisous model to extract the filamentary structures in different large-scale environments. We study the properties of galaxy groups as a function of their dynamical mass in different large-scale environments. Results. We find differences in the properties of central galaxies and their groups in and outside of filaments at fixed halo and largescale environments. In high-density environments, the group mass function has higher number densities in filaments compared to that outside of filaments towards the massive end. The relation is opposite in low-density environments. At fixed group mass and largescale luminosity density, mass-to-light ratios show that groups in filaments are slightly more luminous than those outside of filaments. At fixed group mass and large-scale luminosity density, central galaxies in filaments have redder colors, higher stellar masses, and lower specific star formation rates than those outside of filaments. However, the differences in central galaxy and group properties in and outside of filaments are not clear in some group mass bins. We show that the differences in central galaxy properties are due to the higher abundances of elliptical galaxies in filaments. Conclusions. Filamentary structures in the cosmic web are not simply visual associations of galaxies, but rather play an important role in shaping the properties of groups and their central galaxies. The differences in central galaxy and group properties in and outside of cosmic web filaments are not simple effects related to large-scale environmental density. The results point towards an efficient mechanism in cosmic web filaments which quench star formation and transform central galaxy morphology from late to early types.

The Effect of Filaments and Tendrils on the H i Content of Galaxies

“…Kuutma et al (2017) find that at fixed density, high-mass galaxies (M r < −20 mag) within filaments have reduced star formation rates (but not higher masses) and are more likely to have early-type morphologies. Poudel et al (2017) find that at fixed group mass and environmental density, groups in filaments are more luminous, and central galaxies in filaments have redder colors, higher masses, and lower specific star formation rates.…”

Discovery of the Kinematic Alignment of Early-type Galaxies in the Virgo Cluster

“…In filaments, several observational studies (Codis et al 2012;Tempel et al , 2015Tempel & Libeskind 2013;Hirv et al 2017) indicate that the major axes (perpendicular to spin axes) of early-type galaxies are expected to be aligned with the direction of the host filaments because major mergers that form early-type galaxies occur along the filament, making their major axes parallel to the directions of the filaments. Furthermore, in filaments, central galaxies in groups tend to be early-type galaxies compared with galaxies outside of the filaments (e.g., Kuutma et al 2017;Poudel et al 2017). This suggests that the filament environment could efficiently transform the galaxy morphology from late-to early-type.…”

The environment of H i-bearing ultra-diffuse galaxies in the ALFALFA survey

“…They worked in a probabilistic Bayesian framework and adopted a filament radius of 0.5h −1 Mpc. Previous work using these catalogs has shown that being inside a filament affects galaxy properties even when comparing with non-filament galaxies at fixed local (aperture) density (Poudel et al 2017). When determining the distance to the nearest filament for each member of our HUDs samples, we first limit our calculations to those that are fully enclosed by the volume of the Tempel et al (2014) catalog.…”