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(Institute of Physics, 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.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 ALMA Observations of Gas-rich Galaxies in z ∼ 1.6 Galaxy Clusters: Evidence for Higher Gas Fractions in High-density Environments(Institute of Physics Publishing, 2017-06) Noble A.G.; Donald M.; Muzzin A.; Nantais J.; Rudnick G.; Van Kampen E.; Webb T.M.A.; Wilson G.; Yee H.K.C.; Boone K.; Cooper M.C.; DeGroot A.; Delahaye A.; Demarco R.; Foltz R.; Hayden B.; Lidman C.; Manilla-Robles A.; Perlmutter S.We present ALMA CO (2-1) detections in 11 gas-rich cluster galaxies at z ∼ 1.6, constituting the largest sample of molecular gas measurements in z > 1.5 clusters to date. The observations span three galaxy clusters, derived from the Spitzer Adaptation of the Red-sequence Cluster Survey. We augment the >5σ detections of the CO (2-1) fluxes with multi-band photometry, yielding stellar masses and infrared-derived star formation rates, to place some of the first constraints on molecular gas properties in z ∼ 1.6 cluster environments. We measure sizable gas reservoirs of 0.5-2 × 1011 M in these objects, with high gas fractions (f gas) and long depletion timescales (τ), averaging 62% and 1.4 Gyr, respectively. We compare our cluster galaxies to the scaling relations of the coeval field, in the context of how gas fractions and depletion timescales vary with respect to the star-forming main sequence. We find that our cluster galaxies lie systematically off the field scaling relations at z = 1.6 toward enhanced gas fractions, at a level of ∼4σ, but have consistent depletion timescales. Exploiting CO detections in lower-redshift clusters from the literature, we investigate the evolution of the gas fraction in cluster galaxies, finding it to mimic the strong rise with redshift in the field. We emphasize the utility of detecting abundant gas-rich galaxies in high-redshift clusters, deeming them as crucial laboratories for future statistical studies. © 2017. The American Astronomical Society. All rights reserved.Ítem GOGREEN: A critical assessment of environmental trends in cosmological hydrodynamical simulations at z ≈ 1(Oxford University Press, 2023-01) Kukstas, Egidijus; Balogh, Michael L.; Mccarthy, Ian G.; Bahe, 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.; Zaritsky, 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. © 2022 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.Ítem The Evolution of Environmental Quenching Timescales to z ∼ 1.6: Evidence for Dynamically Driven Quenching of the Cluster Galaxy Population(Institute of Physics Publishing, 2018-10) Foltz R.; Wilson G.; Muzzin A.; Cooper M.C.; Nantais J.; Van Der Burg R.F.J.; Cerulo P.; Chan J.; Fillingham S.P.; Surace J.; Webb T.; Noble A.; McDonald M.; Rudnick G.; Lidman C.; Demarco R.; Hlavacek-Larrondo J.; Yee H.K.C.; Perlmutter S.; Hayden B.Using a sample of four galaxy clusters at 1.35 < z < 1.65 and 10 galaxy clusters at 0.85 < z < 1.35, we measure the environmental quenching timescale, t Q, corresponding to the time required after a galaxy is accreted by a cluster for it to fully cease star formation. Cluster members are selected by a photometric-redshift criterion, and categorized as star-forming, quiescent, or intermediate according to their dust-corrected rest-frame colors and magnitudes. We employ a "delayed-then-rapid" quenching model that relates a simulated cluster mass accretion rate to the observed numbers of each type of galaxy in the cluster to constrain t Q. For galaxies of mass M ∗ 1010.5 M o, we find a quenching timescale of t Q = Gyr in the z ∼ 1.5 cluster sample, and Gyr at z ∼ 1. Using values drawn from the literature, we compare the redshift evolution of t Q to timescales predicted for different physical quenching mechanisms. We find t Q to depend on host halo mass such that quenching occurs over faster timescales in clusters relative to groups, suggesting that properties of the host halo are responsible for quenching high-mass galaxies. Between z = 0 and z = 1.5, we find that t Q evolves faster than the molecular gas depletion timescale and slower than an estimated star formation rate-outflow timescale, but is consistent with the evolution of the dynamical time. This suggests that environmental quenching in these galaxies is driven by the motion of satellites relative to the cluster environment, although due to uncertainties in the atomic gas budget at high redshift, we cannot rule out quenching due to simple gas depletion. © 2018. The American Astronomical Society. All rights reserved..Ítem The H α star formation main sequence in cluster and field galaxies at z ∼1.6(Oxford University Press, 2020-12) Nantais J.; Wilson G.; Muzzin A.; Old L.J.; Demarco R.; Cerulo P.; Balogh M.; Rudnick G.; Chan J.; Cooper M.C.; Forrest B.; Hayden B.; Lidman C.; Noble A.; Perlmutter S.; Rhea C.; Surace J.; Van Der Burg R.; Van Kampen E.We calculate H α-based star formation rates and determine the star formation rate-stellar mass relation for members of three Spitzer Adaptation of the Red-Sequence Cluster Survey (SpARCS) clusters at z ∼1.6 and serendipitously identified field galaxies at similar redshifts to the clusters. We find similar star formation rates in cluster and field galaxies throughout our range of stellar masses. The results are comparable to those seen in other clusters at similar redshifts, and consistent with our previous photometric evidence for little quenching activity in clusters. One possible explanation for our results is that galaxies in our z ∼1.6 clusters have been accreted too recently to show signs of environmental quenching. It is also possible that the clusters are not yet dynamically mature enough to produce important environmental quenching effects shown to be important at low redshift, such as ram-pressure stripping or harassment. © 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.Ítem The Massive Ancient Galaxies at z > 3 NEar-infrared (MAGAZ3NE) Survey: Confirmation of Extremely Rapid Star Formation and Quenching Timescales for Massive Galaxies in the Early Universe(IOP Publishing Ltd, 2020-11-01) Forrest, Ben; Cemile Marsan Z.; Annunziatella, Marianna; Wilson, Gillian; Muzzin, Adam; Marchesini, Danilo; Cooper M.C.; Chan, Jeffrey C.C.; McConachie, Ian; Gomez, Percy; Kado-Fong, Erin; Barbera, Francesco La; Lange-Vagle, Daniel; Nantais, Julie; Nonino, Mario; Saracco, Paolo; Stefanon, Mauro; van der Burg, Remco F.J.We present near-infrared spectroscopic confirmations of a sample of 16 photometrically selected galaxies with stellar Keck/MOSFIRE masses log(as M*part M*of ) > the 11 Massive at redshift Ancient z > 3 Galaxies from the At XMM-VIDEO z > 3 NEar-infrared and COSMOS-UltraVISTA (MAGAZ3NE) survey. fields Eight using of the ultramassive galaxies (UMGs) have specific star formation rates (sSFR) < 0.03 Gyr−1, with negligible emission lines. Another seven UMGs show emission lines consistent with active galactic nuclei and/or star formation, while only one UMG has sSFR > 1 Gyr−1. Model star formation histories of these galaxies describe systems that formed the majority of their stars in vigorous bursts of several hundred megayear duration around 4 < z < 6 during which hundreds to thousands of solar masses were formed per year. These formation ages of <1 Gyr prior to observation are consistent with ages derived from measurements of Dn(4000) and EW0(Hδ). Rapid quenching followed these bursty star-forming periods, generally occurring less than 350 Myr before observation, resulting in post-starburst SEDs and spectra for half the sample. The rapid formation timescales are consistent with the extreme star formation rates observed in 4 < z < 7 dusty starbursts observed with ALMA, suggesting that such dusty galaxies are progenitors of these UMGs. While such formation histories have been suggested in previous studies, the large sample introduced here presents the most compelling evidence yet that vigorous star formation followed by rapid quenching is almost certainly the norm for high-mass galaxies in the early universe. The UMGs presented here were selected to be brighter than Ks = 21.7, raising the intriguing possibility that even (fainter) older quiescent UMGs could exist at this epoch.