Examinando por Autor "Cooper, M. C."
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Ítem A Large-scale Kinematic Study of Molecular Gas in High-z Cluster Galaxies: Evidence for High Levels of Kinematic Asymmetry(Astrophysical Journal, 2023-02-01) Cramer, W. J.; Noble, A. G.; Massingill, K.; Cairns, J.; Clements, D. L.; Cooper, M. C.; Demarco, R.; Matharu, J.; McDonald, M.; Muzzin, A.; Nantais, J.; Rudnick, G.; Übler, H.; van Kampen, E.; Webb, T. M. A.; Wilson, G.; Yee, H. K. C.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 of z ∼ 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.Ítem The GOGREEN Survey: Evidence of an Excess of Quiescent Disks in Clusters at 1.0(IOP Publishing Ltd, 2021-10-10) Chan, Jeffrey C. C.; Wilson, Gillian; Balogh, Michael; Rudnick, Gregory; van der Burg, Remco F. J.; Muzzin, Adam; Webb, Kristi A.; Biviano, Andrea; Cerulo, Pierluigi; Cooper, M. C.; De Lucia, Gabriella; Demarco, Ricardo; Forrest, Ben; Jablonka, Pascale; Lidman, Chris; McGee, Sean L.; Nantais, Julie; Old, Lyndsay; Pintos-Castro, Irene; Poggianti, Bianca; Reeves, Andrew M. M.; Vulcani, Benedetta; Yee, Howard K. C.; Zaritsky, DennisWe present the results of the measured shapes of 832 galaxies in 11 galaxy clusters at 1.0 < z < 1.4 from the GOGREEN survey. We measure the axis ratio (q), the ratio of the minor to the major axis, of the cluster galaxies from near-infrared Hubble Space Telescope imaging using Sersic profile fitting and compare them with a field sample. We find that the median q of both star-forming and quiescent galaxies in clusters increases with stellar mass, similar to the field. Comparing the axis ratio distributions between clusters and the field in four mass bins, the distributions for star-forming galaxies in clusters are consistent with those in the field. Conversely, the distributions for quiescent galaxies in the two environments are distinct, most remarkably in where clusters show a flatter distribution, with an excess at low q. Modelling the distribution with oblate and triaxial components, we find that the cluster and field sample difference is consistent with an excess of flattened oblate quiescent galaxies in clusters. The oblate population contribution drops at high masses, resulting in a narrower q distribution in the massive population than at lower masses. Using a simple accretion model, we show that the observed q distributions and quenched fractions are consistent with a scenario where no morphological transformation occurs for the environmentally quenched population in the two intermediate-mass bins. Our results suggest that environmental quenching mechanism(s) likely produce a population that has a different morphological mix than those resulting from the dominant quenching mechanism in the field.Ítem GOGREEN: A critical assessment of environmental trends in cosmological hydrodynamical simulations at z ≈ 1(Oxford University Press, 2023-01-01) Kukstas, Egidijus; Balogh, Michael L.; McCarthy, Ian G.; Bahé, Yannick M.; De Lucia, Gabriella; Jablonka, Pascale; Vulcani, Benedetta; Baxter, Devontae C.; Biviano, Andrea; Cerulo, Pierluigi; Chan, Jeffrey C.; Cooper, M. C.; Demarco, Ricardo; Finoguenov, Alexis; Font, Andreea S.; Lidman, Chris; Marchioni, Justin; McGee, Sean; Muzzin, Adam; Nantais, Julie; Old, Lyndsay; Pintos-Castro, Irene; Poggianti, Bianca; Reeves, Andrew M. M.; Rudnick, Gregory; Sarron, Florian; van der Burg, Remco; Webb, Kristi; Wilson, Gillian; Yee, Howard K. C.; Zaritsk, DennisRecent 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* ≲ 1010 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.