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ABSTRACT We explore models of massive (>1010 M⊙) satellite quenching in massive clusters at z ≳ 1 using an MCMC framework, focusing on two primary parameters: Rquench (the host-centric radius at which quenching begins) and τquench (the time-scale upon which a satellite quenches after crossing Rquench). Our MCMC analysis shows two local maxima in the 1D posterior probability distribution of Rquench at approximately 0.25 and 1.0 R200. Analysing four distinct solutions in the τquench–Rquench 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 R200). 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 The cluster mass–richness relation (MRR) is an observationally efficient and potentially powerful cosmological tool for constraining the matter density Ω_mand the amplitude of fluctuationsσ₈using the cluster abundance technique. We derive the MRR relation usingGalWCat19, a publicly available galaxy cluster catalog we created from the Sloan Digital Sky Survey-DR13 spectroscopic data set. In the MRR, cluster mass scales with richness as $\log M_{200}=\alpha +\beta \log N_{200}$. We find that the MRR we derive is consistent with both the IllustrisTNG and mini-Uchuu cosmological numerical simulations, with a slope ofβ≈ 1. We use the MRR we derived to estimate cluster masses from theGalWCat19catalog, which we then use to set constraints on Ω_mandσ₈. Utilizing the all-member MRR, we obtain constraints of Ω_m= ${0.31}_{-0.03}^{+0.04}$andσ₈= ${0.82}_{-0.04}^{+0.05}$, and utilizing the red member MRR only, we obtain Ω_m= ${0.31}_{-0.03}^{+0.04}$andσ₈= ${0.81}_{-0.04}^{+0.05}$. Our constraints on Ω_mandσ₈are consistent and very competitive with the Planck 2018 results. 

Abstract We investigate the resolved kinematics of the molecular gas, as traced by the Atacama Large Millimeter/submillimeter Array in CO (2−1), of 25 cluster member galaxies across three different clusters at a redshift ofz∼ 1.6. This is the first large-scale analysis of the molecular gas kinematics of cluster galaxies at this redshift. By separately estimating the rotation curve of the approaching and receding sides of each galaxy via kinematic modeling, we quantify the difference in total circular velocity to characterize the overall kinematic asymmetry of each galaxy. 3/14 of the galaxies in our sample that we are able to model have similar degrees of asymmetry as that observed in galaxies in the field at similar redshift based on observations of mainly ionized gas. However, this leaves 11/14 galaxies in our sample with significantly higher asymmetry, and some of these galaxies have degrees of asymmetry of up to ∼50 times higher than field galaxies observed at similar redshift. Some of these extreme cases also have one-sided tail-like morphology seen in the molecular gas, supporting a scenario of tidal and/or ram pressure interaction. Such stark differences in the kinematic asymmetry in clusters versus the field suggest the evolutionary influence of dense environments, established as being a major driver of galaxy evolution at low redshift, is also active in the high-redshift universe. 

ABSTRACT Recent observations have shown that the environmental quenching of galaxies at z ∼ 1 is qualitatively different to that in the local Universe. However, the physical origin of these differences has not yet been elucidated. In addition, while low-redshift comparisons between observed environmental trends and the predictions of cosmological hydrodynamical simulations are now routine, there have been relatively few comparisons at higher redshifts to date. Here we confront three state-of-the-art suites of simulations (BAHAMAS+MACSIS, EAGLE+Hydrangea, IllustrisTNG) with state-of-the-art observations of the field and cluster environments from the COSMOS/UltraVISTA and GOGREEN surveys, respectively, at z ∼ 1 to assess the realism of the simulations and gain insight into the evolution of environmental quenching. We show that while the simulations generally reproduce the stellar content and the stellar mass functions of quiescent and star-forming galaxies in the field, all the simulations struggle to capture the observed quenching of satellites in the cluster environment, in that they are overly efficient at quenching low-mass satellites. Furthermore, two of the suites do not sufficiently quench the highest mass galaxies in clusters, perhaps a result of insufficient feedback from AGN. The origin of the discrepancy at low stellar masses ($$M_* \lesssim 10^{10}$$ M⊙), which is present in all the simulations in spite of large differences in resolution, feedback implementations, and hydrodynamical solvers, is unclear. The next generation of simulations, which will push to significantly higher resolution and also include explicit modelling of the cold interstellar medium, may help us to shed light on the low-mass tension.