Examinando por Autor "Rudnick, G."
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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 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.; McDonald, 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.Ítem Gemini Observations of Galaxies in Rich Early Environments (GOGREEN) I: survey description(Oxford University Press, 2017-06) Balogh, M.L.; Gilbank, D.G.; Muzzin, A.; Rudnick, G.; Cooper, M.C.; Lidman, C.; Biviano, A.; Demarco, R.; McGee, S.L.; Nantais, J.B.; Noble, A.; Old, L.; Wilson, G.; Yee, H.K.C.; Bellhouse, C.; Cerulo, P.; Chan, J.; Pintos-Castro, I.; Simpson, R.; van der Burg, R.F.J.; Zaritsky, D.; Ziparo, F.; Alonso, M.V.; Bower, R.G.; Lucia, G.D.; Finoguenov, A.; Lambas, D.G.; Muriel, H.; Parker, L.C.; Rettura, A.; Valotto, C.; Wetzel, A.We describe a new Large Program in progress on the Gemini North and South telescopes: Gemini Observations of Galaxies in Rich Early Environments (GOGREEN). This is an imaging and deep spectroscopic survey of 21 galaxy systems at 1 < z < 1.5, selected to span a factor >10 in halo mass. The scientific objectives include measuring the role of environment in the evolution of low-mass galaxies, and measuring the dynamics and stellar contents of their host haloes. The targets are selected from the SpARCS, SPT, COSMOS, and SXDS surveys, to be the evolutionary counterparts of today's clusters and groups. The newred-sensitive Hamamatsu detectors on GMOS, coupled with the nod-and-shuffle sky subtraction, allow simultaneous wavelength coverage over λ ~ 0.6-1.05 μm, and this enables a homogeneous and statistically complete redshift survey of galaxies of all types. The spectroscopic sample targets galaxies with AB magnitudes z' < 24.25 and [3.6] μm < 22.5, and is therefore statistically complete for stellar masses M* ≳ 1010.3M⊙, for all galaxy types and over the entire redshift range. Deep, multiwavelength imaging has been acquired over larger fields for most systems, spanning u through K, in addition to deep IRAC imaging at 3.6 μm. The spectroscopy is ~50 per cent complete as of semester 17A, and we anticipate a final sample of ~500 new cluster members. Combined with existing spectroscopy on the brighter galaxies from GCLASS, SPT, and other sources, GOGREEN will be a large legacy cluster and field galaxy sample at this redshift that spectroscopically covers a wide range in stellar mass, halo mass, and clustercentric radius.Ítem Resolving CO (2-1) in z ∼ 1.6 Gas-rich Cluster Galaxies with ALMA: Rotating Molecular Gas Disks with Possible Signatures of Gas Stripping(Astrophysical Journal, 2019-01-10) Noble, A.G.; Muzzin, A.; McDonald, M.; Rudnick, G.; Matharu, J.; Cooper, M.C.; Demarco, R.; Lidman, C.; Nantais, J.; Van Kampen, E.; Webb, T.M.A.; Wilson, G.; Yee, H.K.C.We present the first spatially resolved observations of molecular gas in a sample of cluster galaxies beyond z > 0.1. Using ALMA, we detect CO (2-1) in eight z ∼ 1.6 cluster galaxies, all within a single 70″ primary beam. The cluster, SpARCS-J0225, was discovered by the Spitzer Adaptation of the Red-sequence Cluster Survey, and is replete with gas-rich galaxies in close proximity, thus affording an efficient multiplexing strategy to amass the first sample of resolved CO in distant clusters. Mapping out the kinematic structure and morphology of molecular gas on ∼3.5 kpc scales reveals rotating gas disks in the majority of the galaxies, and some kinematic peculiarities, including a central gas void, a merger, and one-sided gas tails. We find that the extent of the molecular gas is slightly smaller than that of the optical HST stellar component; this is even more pronounced in low-redshift Virgo cluster galaxies. However, limited by small sample sizes of spatially resolved CO, we are unable to differentiate the distribution of stellar-to-gas radii between cluster and field environments at high redshift. Thus, at first glance, while the cluster galaxies generally look like galaxies infalling from the field, with typical main-sequence star formation rates and massive molecular gas reservoirs situated in rotating disks, they have potentially remarkable attributes, including elevated gas fractions, slightly smaller CO disks, and asymmetric gas tails. Taken in tandem, these signatures are tentative evidence for gas stripping in the z ∼ 1.6 cluster, though verification of these trends will require larger samples.