Brightest group galaxies and the large-scale environment

TL;DR

This study investigates how the large-scale environment influences the properties of brightest group galaxies, revealing significant effects on late-type galaxies but not on early-types, using SDSS-DR7 data.

Contribution

It demonstrates that large-scale structures impact the properties of late-type brightest group galaxies beyond local group effects.

Findings

Late-type brightest galaxies are more luminous and massive in superstructures.

Late-type brightest galaxies are redder with lower star formation in superstructures.

Early-type brightest galaxies show no significant environmental dependence.

Abstract

We study the dependence of the properties of group galaxies on the surrounding large-scale environment, using SDSS-DR7 data. Galaxies are ranked according to their luminosity within each group and classified morphologically by the S\'ersic index. We have considered samples of the host groups in superstructures of galaxies, and elsewhere. We find a significant dependence of the properties of late-type brightest group galaxies on the large-scale environment: they show statistically significant higher luminosities and stellar masses, redder u-r colours, lower star formation activity and longer star-formation time-scale when embedded in superstructures. By contrast, the properties of the early-type brightest group galaxies are remarkably similar regardless of the group global environment. The other group member galaxies exhibit only the local influence of the group they inhabit. Our analysis comprises tests against the dependence on the host group luminosity and we argue that group brightest member properties are not only determined by the host halo, but also by the large-scale structure which can influence the accretion process onto their late-type brightest galaxies.