Examinando por Autor "Valotto, Carlos"
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Ítem Galaxy clustering in the VVV near-IR galaxy catalogue(Oxford University Press, 2022-06-01) Soto, Mario; Sgró, Mario A.; Baravalle, Laura D.; Alonso, M. Victoria; Nilo Castellón, José Luis; Valotto, Carlos; Taverna, Antonela; Díaz-Giménez, Eugenia; Villalón, Carolina; Minniti, DanteMapping galaxies at low Galactic latitudes and determining their clustering status are fundamental steps in defining the large-scale structure in the nearby Universe. The VISTA Variables in the Vía Láctea (VVV) near-IR galaxy catalogue (VVV NIRGC) allows us to explore this region in great detail. Our goal is to identify galaxy overdensities and characterize galaxy clustering in the Zone of Avoidance. We use different clustering algorithms to identify galaxy overdensities: the Voronoi tessellations, the minimum spanning tree, and the ordering points to identify the clustering structure. We studied the membership, isolation, compactness, and flux limits to identify compact groups of galaxies. Each method identified a variety of galaxy systems across the Galactic plane that are publicly available. We also explore the probability that these systems are formed by concordant galaxies using mock catalogues. 19 galaxy systems were identified in all of the four methods. They have the highest probability to be real overdensities. We stress the need for spectroscopic follow-up observations to confirm and characterize these new structures. © 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.Ítem Gemini Observations of Galaxies in Rich Early Environments (GOGREEN) I: Survey description(Oxford University Press, 2017-10) Balogh, Michael L.; Gilbank, David G.; Muzzin, Adam; Rudnick, Gregory; Cooper, Michael C.; Lidman, Chris; Biviano, Andrea; Demarco, Ricardo; McGee, Sean L.; Nantais, Julie B.; Noble, Allison; Old, Lyndsay; Wilson, Gillian; Yee, Howard K.C.; Bellhouse, Callum; Cerulo, Pierluigi; Chan, Jeffrey; Pintos-Castro, Irene; Simpson, Rane; van der Burg, Remco F.J.; Zaritsky, Dennis; Ziparo, Felicia; Alonso, María Victoria; Bower, Richard G.; Lucia, Gabriella De; Finoguenov, Alexis; Lambas, Diego Garcia; Muriel, Hernan; Parker, Laura C.; Rettura, Alessandro; Valotto, Carlos; Wetzel, AndrewWe 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. © 2017 The Authors.Ítem LOW X-RAY LUMINOSITY GALAXY CLUSTERS: MAIN GOALS, SAMPLE SELECTION, PHOTOMETRIC AND SPECTROSCOPIC OBSERVATIONS(IOP PUBLISHING, 2016-06) Nilo Castellón, José Luis; Alonso, M. Victoria; García Lambas, Diego; Valotto, Carlos; O' Mill, Ana Laura; Cuevas, Héctor; Carrasco, Eleazar R.; Ramírez, Amelia; Astudillo, José M.; Ramos, Felipe; Jaque Arancibia, Marcelo; Ulloa, Natalie; Órdenes, YasnaWe present our study of 19 low X-ray luminosity galaxy clusters (L-X similar to 0.5-45. x. 10(43) erg s(-1)), selected from the ROSAT Position Sensitive Proportional Counters Pointed Observations and the revised version of Mullis et al. in the redshift range of 0.16-0.7. This is the introductory paper of a series presenting the sample selection, photometric and spectroscopic observations, and data reduction. Photometric data in different passbands were taken for eight galaxy clusters at Las Campanas Observatory; three clusters at Cerro Tololo Interamerican Observatory; and eight clusters at the Gemini Observatory. Spectroscopic data were collected for only four galaxy clusters using Gemini telescopes. Using the photometry, the galaxies were defined based on the star-galaxy separation taking into account photometric parameters. For each galaxy cluster, the catalogs contain the point-spread function and aperture magnitudes of galaxies within the 90% completeness limit. They are used together with structural parameters to study the galaxy morphology and to estimate photometric redshifts. With the spectroscopy, the derived galaxy velocity dispersion of our clusters ranged from 507 km s(-1) for [VMF98]022 to 775 km s-1 for [VMF98] 097 with signs of substructure. Cluster membership has been extensively discussed taking into account spectroscopic and photometric redshift estimates. In this sense, members are the galaxies within a projected radius of 0.75 Mpc from the X-ray emission peak and with clustercentric velocities smaller than the cluster velocity dispersion or 6000 km s(-1), respectively. These results will be used in forthcoming papers to study, among the main topics, the red cluster sequence, blue cloud and green populations, the galaxy luminosity function, and cluster dynamics.Ítem The VVV near-IR galaxy catalogue beyond the Galactic disc(Monthly Notices of the Royal Astronomical Society, 2021-03) Baravalle, Laura D; Alonso, María Victoria; Minniti, Dante; Nilo Castellón, José Luis; Soto, Mario; Valotto, Carlos; Villalón, Carolina; Graña, Darío; Amôres, Eduardo B; Milla Castro, FernandaKnowledge about the large-scale distribution of galaxies is far from complete in the Zone of Avoidance (ZoA), which is mostly due to high interstellar extinction and to source confusion at lower Galactic latitudes. Past near-infrared (NIR) surveys, such as the Two Micron All Sky Survey (2MASS), have shown the power of probing large-scale structure at these latitudes. Our aim is to map the galaxy distribution across the Southern Galactic plane using the VISTA Variables in the Vía Láctea Survey (VVV), which reach 2-4 mag deeper than 2MASS. We used SExtractor+PSFEx to identify extended objects and to measure their sizes, the light concentration index, magnitudes, and colours. Morphological and colour constraints and visual inspection were used to confirm galaxies. We present the resulting VVV NIR Galaxy Catalogue (VVV NIRGC) of 5563 visually confirmed galaxies, of which only 45 were previously known. This is the largest catalogue of galaxies towards the Galactic plane, with 99 per cent of these galaxies being new discoveries. We found that the galaxy density distribution closely resembled the distribution of low interstellar extinction of the existing NIR maps. We also present a description of the 185 2MASS extended sources observed in the region, of which 16 per cent of these objects had no previous description, which we have now classified. We conclude that interstellar extinction and stellar density are the main limitations for the detection of background galaxies in the ZoA. The VVV NIRGC is a new data set providing information for extragalactic studies in the Galactic plane. © 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.