VIS3COS. III. Galaxy spectra

This indicates that field galaxies with low stellar mass and lament galaxies with high stellar mass are more likely to have experienced a recent burst of star formation, while galaxies of the intermediate stellar-mass show an increase of star formation at lament-like densities. We also find that the median [OII] equivalent width (|EW[OII]|) decreases from 27+/-2{AA} to 2.0^+0,5^_-0.4_{AA} and Dn4000 increases from 1.09+/-0.01 to 1.56+/-0.03 with increasing stellar mass (from ~10^9.25^ to ~10^11.35^M_{sun}_).

For the dependence on the environment, we find that at fixed stellar mass, |EW[OII]| is tentatively lower in environments with higher density. We find for Dn4000 that the increase with stellar mass is sharper in denser environments, which indicates that these environments may accelerate galaxy evolution. Moreover, we find higher Dn4000 values in denser environments at fixed stellar mass, suggesting that galaxies are on average older and/or more metal rich in these dense environments.

This set of tracers depicts a scenario where the most massive galaxies have, on average, the lowest specic star formation rates and the oldest stellar populations (age>~1Gyr, showing a mass-downsizing eect). We also hypothesize that the observed increase in star formation (higher EW[OII], higher specic star formation rate) at intermediate densities may lead to quenching because we find that the quenched fraction increases sharply from the lament to cluster-like regions at similar stellar masses.