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We present an analysis of the galaxy stellar mass function (SMF) of 14 known protoclusters between 2.0 < z < 2.5 in the COSMOS field, down to a mass limit of 109.5 M⊙. We use existing photometric redshifts with a statistical background subtraction, and consider star-forming and quiescent galaxies identified from (NUV − r) and (r − J) colours separately. Our fiducial sample includes galaxies within 1 Mpc of the cluster centres. The shape of the protocluster SMF of star-forming galaxies is indistinguishable from that of the general field at this redshift. Quiescent galaxies, however, show a flatter SMF than in the field, with an upturn at low mass, though this is only significant at ∼2σ. There is no strong evidence for a dominant population of quiescent galaxies at any mass, with a fraction <15 per cent at 1σ confidence for galaxies with log  M */ M ⊙ < 10.5. We compare our results with a sample of galaxy groups at 1 < z < 1.5, and demonstrate that a significant amount of environmental quenching must take place between these epochs, increasing the relative abundance of high-mass (⁠|$\rm M_{\ast } \gt 10^{10.5} {\rm M}_{\odot }$|⁠) quiescent galaxies by a factor ≳ 2. However, we find that at lower masses (⁠|$\rm M_{\ast } \lt 10^{10.5} {\rm M}_{\odot }$|⁠), no additional environmental quenching is required. [ABSTRACT FROM AUTHOR]

We explore models of massive (>1010 M⊙) satellite quenching in massive clusters at z ≳ 1 using an MCMC framework, focusing on two primary parameters: R quench (the host-centric radius at which quenching begins) and τquench (the time-scale upon which a satellite quenches after crossing R quench). Our MCMC analysis shows two local maxima in the 1D posterior probability distribution of R quench at approximately 0.25 and 1.0  R 200. Analysing four distinct solutions in the τquench– R quench parameter space, nearly all of which yield quiescent fractions consistent with observational data from the GOGREEN survey, we investigate whether these solutions represent distinct quenching pathways and find that they can be separated between 'starvation' and 'core quenching' scenarios. The starvation pathway is characterized by quenching time-scales that are roughly consistent with the total cold gas (H2 + H  i) depletion time-scale at intermediate z , while core quenching is characterized by satellites with relatively high line-of-sight velocities that quench on short time-scales (∼0.25 Gyr) after reaching the inner region of the cluster (<0.30  R 200). Lastly, we break the degeneracy between these solutions by comparing the observed properties of transition galaxies from the GOGREEN survey. We conclude that only the 'starvation' pathway is consistent with the projected phase-space distribution and relative abundance of transition galaxies at z ∼ 1. However, we acknowledge that ram pressure might contribute as a secondary quenching mechanism. [ABSTRACT FROM AUTHOR]

We model satellite quenching at z ∼ 1 by combining 14 massive (1013.8 < M halo/M⊙ < 1015) clusters at 0.8 < z < 1.3 from the GOGREEN and GCLASS surveys with accretion histories of 56 redshift-matched analogues from the IllustrisTNG simulation. Our fiducial model, which is parametrized by the satellite quenching time-scale (τquench), accounts for quenching in our simulated satellite population both at the time of infall by using the observed coeval field quenched fraction and after infall by tuning τquench to reproduce the observed satellite quenched fraction versus stellar mass trend. This model successfully reproduces the observed satellite quenched fraction as a function of stellar mass (by construction), projected cluster-centric radius, and redshift and is consistent with the observed field and cluster stellar mass functions at z ∼ 1. We find that the satellite quenching time-scale is mass dependent, in conflict with some previous studies at low and intermediate redshift. Over the stellar mass range probed (M ⋆ > 1010 M⊙), we find that the satellite quenching time-scale decreases with increasing satellite stellar mass from ∼1.6 Gyr at 1010 M⊙ to ∼0.6−1 Gyr at 1011 M⊙ and is roughly consistent with the total cold gas (HI + H2) depletion time-scales at intermediate z , suggesting that starvation may be the dominant driver of environmental quenching at z < 2. Finally, while environmental mechanisms are relatively efficient at quenching massive satellites, we find that the majority (⁠|$\sim 65{\!-\!}80{{\ \rm per\ cent}}$|⁠) of ultra-massive satellites (M ⋆ > 1011 M⊙) are quenched prior to infall. [ABSTRACT FROM AUTHOR]

Using public data from the NEWFIRM Medium-Band Survey (NMBS) and the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS), we investigate the population of massive galaxies at z > 3. The main aim of this work is to identify the potential progenitors of z ~ 2 compact, massive, quiescent galaxies (CMQGs), furthering our understanding of the onset and evolution of massive galaxies. Our work is enabled by high-resolution images from CANDELS data and accurate photometric redshifts, stellar masses, and star formation rates (SFRs) from 37-band NMBS photometry. The total number of massive galaxies at z > 3 is consistent with the number of massive, quiescent galaxies (MQGs) at z ~ 2, implying that the SFRs for all of these galaxies must be much lower by z ~ 2. We discover four CMQGs at z > 3, pushing back the time for which such galaxies have been observed. However, the volume density for these galaxies is significantly less than that of galaxies at z < 2 with similar masses, SFRs, and sizes, implying that additional CMQGs must be created in the intervening ~1 Gyr between z = 3 and z = 2. We find five star-forming galaxies at z ~ 3 that are compact (Re < 1.4 kpc) and have stellar mass M" > 1010.6M☉; these galaxies are likely to become members of the massive, quiescent, compact galaxy population at z ~ 2. We evolve the stellar masses and SFRs of each individual z > 3 galaxy adopting five different star formation histories (SFHs) and studying the resulting population of massive galaxies at z = 2.3. We find that declining or truncated SFHs are necessary to match the observed number density of MQGs at z ~ 2, whereas a constant delayed-exponential SFH would result in a number density significantly smaller than observed. All of our assumed SFHs imply number densities of CMQGs at z ~ 2 that are consistent with the observed number density. Better agreement with the observed number density of CMQGs at z ~ 2 is obtained if merging is included in the analysis and better still if star formation quenching is assumed to shortly follow the merging event, as implied by recent models of the formation of MQGs. [ABSTRACT FROM AUTHOR]