The enhancement of rapidly quenched galaxies in distant clusters at 0.5 < z < 1.0

Abstract

We investigate the relationship between environment and galaxy evolution in the redshift range 0.5 < z < 1.0. Galaxy overdensities are selected using a Friends-of-Friends algorithm, applied to deep photometric data in the Ultra-Deep Survey (UDS) field. A study of the resulting stellar mass functions reveals clear differences between cluster and field environments, with a strong excess of low-mass rapidly quenched galaxies in cluster environments compared to the field. Cluster environments also show a corresponding deficit of young, low-mass star-forming galaxies, which show a sharp radial decline towards cluster centres. By comparing mass functions and radial distributions, we conclude that young star-forming galaxies are rapidly quenched as they enter overdense environments, becoming post-starburst galaxies before joining the red sequence. Our results also point to the existence of two environmental quenching pathways operating in galaxy clusters, operating on different timescales. Fast quenching acts on galaxies with high specific star-formation rates, operating on timescales shorter than the cluster dynamical time (< 1 Gyr). In contrast, slow quenching affects galaxies with moderate specific star-formation rates, regardless of their stellar mass, and acts on longer timescales ( 1 Gyr). Of the cluster galaxies in the stellar mass range 9.0 < log(M/M ) < 10.5 quenched during this epoch, we find that 73% were transformed through fast quenching, while the remaining 27% followed the slow quenching route. Peng et al. (2010) compare the stellar mass and environment of galaxies with their star formation rate (SFR), and conclude that there are two separate quenching processes that cause galaxies to cease forming stars. They call these processes "environmental quenching" and "mass quenching". The efficiency of environmental quenching depends on the environment of a galaxy, such that galaxies in high density environments are more likely to be quenched. Independently, the efficiency of mass quenching correlates with the stellar mass of the galaxy, such that more massive galaxies are more likely to be quenched. Additionally, there is morphological quenching (Martig et al. 2009), in which the structure of the galaxy changes first, leading to a more stable configuration which prevents gas from collapsing into stars. However, the physical processes that are responsible for these quenching pathways remain unclear.The most popular mechanisms used to explain mass

Compact star-forming galaxies preferentially quenched to become PSBs inz< 1 clusters

“…In contrast, the observed number of quenched low-mass galaxies increases towards the present day (Drory et al 2009;Baldry et al 2012;Moutard et al 2016Moutard et al , 2018. This downsizing in the passive population is generally associated with environmental quenching, and has been measured up to z ∼ 1 (Muzzin et al 2013;Tomczak et al 2014;Socolovsky et al 2018). These evolutionary trends are consistent with galaxies in high-density E-mail: miguel.socolovsky@nottingham.ac.uk environments being more likely to be passive regardless of their stellar mass (Balogh et al 1997;Baldry et al 2006;Yang et al 2009;Peng et al 2010;Hartley et al 2013).…”

“…The most depleted population in clusters are those with low stellar masses and high specific star formation rates (SSFRs). In Socolovsky et al (2018) we showed that these high SSFR galaxies are likely to evolve into low-mass poststarbursts (PSBs) in dense environments at 0.5 < z < 1.0. By studying the stellar-mass function, we found a significant excess of low-mass PSBs in clusters.…”

“…In Section 2 we present our data, the classification method and a description of how structural parameters are measured from ground-based imaging. We also present a brief description of the cluster-finding algorithm, developed in Socolovsky et al (2018). We present our results in Section 3 and discuss their possible implications in Section 4.…”

On the Gas Content, Star Formation Efficiency, and Environmental Quenching of Massive Galaxies in Protoclusters at z ≈ 2.0–2.5

“…Over the past two decades, studies of clusters beyond the local Universe and up to high redshifts (z ∼ 1.5) have found a similar bimodality between galaxies' properties and density, such that the denser areas, corresponding to galaxy clusters, contain a higher fraction of quiescent massive elliptical galaxies than the less dense environments typical of the average field density (Balogh et al 1999;Scoville et al 2007aScoville et al , 2013Peng et al 2010;McGee et al 2011;Muzzin et al 2012;Papovich et al 2012;Newman et al 2014;Socolovsky et al 2018;Strazzullo et al 2018). Therefore, in order to understand the physical origin of this dichotomy, a problem still under debate, observations of clusters at earlier epochs, particularly during the earliest phases of assembly, are required.…”

Galaxy kinematics across different environments in the RXJ1347−1145 cluster complex

“…Recently, some Based on observations with the European Southern Observatory Very Large Telescope (ESO-VLT), observing runs ID 386.A-0688(D) and 087.A-0361(D). studies have linked the under-abundance of star-forming galaxies in clusters to an excess in the population of post-starburst galaxies in clusters at low to intermediate redshifts (Socolovsky et al 2018, Paccagnella et al 2019, pointing once again towards the influence of the environment in galaxy transformation and the quenching of star formation. However, the exact mechanism causing the stop of star formation is still a matter of debate, with recent studies proposing a two-phase process where a galaxy first slowly consumes most of its gas reservoir in the outskirts of the cluster before being fully quenched due to ram pressure stripping (RPS) in the innermost regions (Petropoulou et al 2011, Wetzel et al 2013, Ciocan et al 2019).…”