Abstract
ABSTRACT We present a study of a sample of 254 clusters from the SDSS-DR7 Yang Catalogue and an auxiliary sample of field galaxies to perform a detailed investigation on how galaxy quenching depends on both environment and galaxy stellar mass. Our samples are restricted to 0.03 ≤ z ≤ 0.1 and we only consider clusters with log (Mhalo/M⊙) ≥ 14. Comparing properties of field and cluster galaxies in the blue cloud, green valley, and red sequence, we find evidence that field galaxies in the red sequence hosted star formation events $\rm 2.1 \pm 0.7$ Gyr ago, on average, more recently than galaxies in cluster environments. Dissecting the star formation rate versus stellar mass diagram we show how morphology rapidly changes after reaching the green valley region, while the star formation rate keeps decreasing. In addition, we use the relation between location in the projected phase space and infall time to explore the time delay between morphological and specific star formation rate variations. We estimate that the transition from late- to early-type morphology happens in Δtinf ∼ 1 Gyr, whereas the quenching of star formation takes ∼3 Gyr. The time-scale we estimate for morphological transitions is similar to the expected for the delayed-then-rapid quenching model. Therefore, we suggest that the delay phase is characterized mostly by morphological transition, which then contributes morphological quenching as an additional ingredient in galaxy evolution.
Highlights
Galaxies and their evolution across cosmic time have always intrigued astronomers
Dividing the star formation rate vs stellar mass diagram into slices of ΔSFMS, we find that, by the end of the green valley, the morphology distribution has a slight peak at early-type shapes, which becomes extremely prominent as we approach the middle of the red sequence
In this paper we investigate the dependence of galaxy evolution on its host environment and provide a detailed view of the galaxy transition from the Blue Cloud to the Red Sequence
Summary
Galaxies and their evolution across cosmic time have always intrigued astronomers. In the first half of the twentieth century, Edwin Hubble classified galaxies according to their morphology (Hubble 1926), defining two major classes: Early Type (ETGs) – characterized by elliptical shapes – and Late Type Galaxies (LTGs) – which comprise galaxies that are a combination of a central bulge and spiral arms. Using the PPS, Pasquali et al (2019) show pre-processed galaxies – those that were already part of a minor group before infalling – to have different properties from those first experiencing the cluster environment. The complex relation between infall time, galaxy properties and quenching mechanisms translates to a variety of paths for galaxy’s transition from the BC to RS. We focus on understanding what defined different stages of galaxy evolution and address the question on whether SFR or morphology changes more quickly in cluster environments. We compare properties of galaxies with different mass and at different environments; in § 5 we define and probe the PPS of galaxy clusters to address variations in morphology and SFR with respect to infall time of member galaxies; in § 6 we discuss our findings; in § 7 we present our final conclusions and a summary.
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