Galaxy quenching in various environments

Already early studies of the morphology-density relation of galaxies showed that
early-type galaxies lie in the centres of rich clusters, and in small groups in filaments
between clusters, where they are located closer to filament axis than late-type galaxies.
This means that galaxies are indeed pre-processed in groups.

In our present study we searched for quenched galaxies (similar to galaxies
in the centres of rich clusters, with the high values of the Dn(4000) parameter)
in other environments using SDSS data. We defined global environment using
luminosity-density field, and local environment as group membership, where we analysed
separately the properties of the brightest group galaxies and satellites.

Our study showed that in the lowest global density environment most galaxies
are either single or members of very poor groups. Still, approximately 1/3 of
all galaxies there are quenched, with very old stellar populations.
The distribution of the stellar masses and other properties of single galaxies in all environments
are very similar to those of satellite galaxies in high-luminosity clusters.
The largest differences are between the brightest group galaxies and satellites, for both
high- and low-luminosity groups.
Our study shows that, indeed, quenching occurs in groups and among single galaxies
both in cluster regions of influence, and far from clusters, in the low-density environments.

References:
ME 1991 (https://ui.adsabs.harvard.edu/abs/1991MNRAS.252..261E/abstract,
https://ui.adsabs.harvard.edu/abs/1991MNRAS.250..802E/abstract)

Einasto et al. 2020 (A&A 641, A172, https://ui.adsabs.harvard.edu/abs/2020A%26A...641A.172E/abstract),
2021 (A&A, 649, A51, https://ui.adsabs.harvard.edu/abs/2021A%26A...649A..51E/abstract),
2022 (A&A, 668, A69,  
(https://ui.adsabs.harvard.edu/abs/2022A%26A...668A..69E/abstract)