Examinando por Autor "Infante, L."

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    Spectroscopic characterization of galaxy clusters in RCS-1: Spectroscopic confirmation, redshift accuracy, and dynamical mass-richness relation
    (Oxford University Press, 2018-05) Gilbank, D.G.; Barrientos, L.F.; Ellingson, E.; Blindert, K.; Yee, H.K.C.; Anguita, T.; Gladders, M.D.; Hall, P.B.; Hertling, G.; Infante, L.; Yan, R.; Carrasco, M.; Garcia-Vergara, C.; Dawson, K.S.; Lidman, C.; Morokuma, T.
    We present follow-up spectroscopic observations of galaxy clusters from the first Red-sequence Cluster Survey (RCS-1). This work focuses on two samples, a lower redshift sample of ~30 clusters ranging in redshift from z~0.2-0.6 observedwith multiobject spectroscopy (MOS) on 4-6.5-m class telescopes and a z ~ 1 sample of ~10 clusters 8-m class telescope observations. We examine the detection efficiency and redshift accuracy of the now widely used redsequence technique for selecting clusters via overdensities of red-sequence galaxies. Using both these data and extended samples including previously published RCS-1 spectroscopy and spectroscopic redshifts from SDSS, we find that the red-sequence redshift using simple twofilter cluster photometric redshifts is accurate to σz ≈ 0.035(1 + z) in RCS-1. This accuracy can potentially be improved with better survey photometric calibration. For the lower redshift sample, ~5 per cent of clusters show some (minor) contamination from secondary systems with the same red-sequence intruding into the measurement aperture of the original cluster. At z ~ 1, the rate rises to ~20 per cent. Approximately ten per cent of projections are expected to be serious, where the two components contribute significant numbers of their red-sequence galaxies to another cluster. Finally, we present a preliminary study of the mass-richness calibration using velocity dispersions to probe the dynamical masses of the clusters. We find a relation broadly consistent with that seen in the local universe from the WINGS sample at z ~ 0.05. © 2018 The Author(s).
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    The ALMA Frontier Fields Survey: V. ALMA Stacking of Lyman-Break Galaxies in Abell 2744, Abell 370, Abell S1063, MACSJ0416.1-2403 and MACSJ1149.5+2223
    (EDP Sciences, 2020-01) Carvajal, R.; Bauer, F.; Bouwens, R.; Oesch, P.; Gonzalez-Lopez, J.; Anguita, T.; Aravena, M.; Demarco, R.; Guaita, L.; Infante, L.; Kim, S.; Kneiss., R.; Koekemoer, A.; Messias, H.; Treister, E.; Villard, E.; Zitrin, A.; Troncoso, P.
    Context. The Hubble Frontier Fields offer an exceptionally deep window into the high-redshift universe, covering a substantially larger area than the Hubble Ultra-Deep field at low magnification and probing 1-2 mag deeper in exceptional high-magnification regions. This unique parameter space, coupled with the exceptional multi-wavelength ancillary data, can facilitate for useful insights into distant galaxy populations. Aims. We aim to leverage Atacama Large Millimetre Array (ALMA) band 6 (≈263 GHz) mosaics in the central portions of five Frontier Fields to characterize the infrared (IR) properties of 1582 ultraviolet (UV)-selected Lyman-Break Galaxies (LBGs) at redshifts of z  ∼  2-8. We investigated individual and stacked fluxes and IR excess (IRX) values of the LBG sample as functions of stellar mass (M⋆ ), redshift, UV luminosity and slope β, and lensing magnification. Methods. LBG samples were derived from color-selection and photometric redshift estimation with Hubble Space Telescope photometry. Spectral energy distributions -templates were fit to obtain luminosities, stellar masses, and star formation rates for the LBG candidates. We obtained individual IR flux and IRX estimates, as well as stacked averages, using both ALMA images and u-v visibilities. Results. Two (2) LBG candidates were individually detected above a significance of 4.1-σ, while stacked samples of the remaining LBG candidates yielded no significant detections. We investigated our detections and upper limits in the context of the IRX-M⋆ and IRX-β relations, probing at least one dex lower in stellar mass than past studies have done. Our upper limits exclude substantial portions of parameter space and they are sufficiently deep in a handful of cases to create mild tension with the typically assumed attenuation and consensus relations. We observe a clear and smooth trend between M⋆ and β, which extends to low masses and blue (low) β values, consistent with expectations from previous works.
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    The alma spectroscopic survey in the hubble ultra deep field: search for [CII] line and dust emission in 6 < z < 8 galaxies
    (Institute of Physics Publishing, 2016-12) Aravena, M.; Decarli, R.; Walter, F.; Bouwens, R.; Oesch, P.A.; Carilli, C.L.; Bauer, F.E.; Cunha, E. Da; Daddi, E.; Gónzalez-López, J.; Ivison, R.J.; Riechers, D.A.; Smail, I.; Swinbank, A.M.; Weiss, A.; Anguita, T.; Bacon, R.; Bell, E.; Bertoldi, F.; Cortes, P.; Cox, P.; Hodge, J.; Ibar, E.; Inami, H.; Infante, L.; Karim, A.; Magnelli, B.; Ota, K.; Popping, G.; Van Der, Werf P.; Wagg, J.; Fudamoto, Y.
    We present a search for [C II] line and dust continuum emission from optical dropout galaxies at z > 6 using ASPECS, our Atacama Large Millimeter submillimeter Array Spectroscopic Survey in the Hubble Ultra-deep Field (UDF). Our observations, which cover the frequency range of 212–272 GHz, encompass approximately the range of 6 < z < 8 for [C II] line emission and reach a limiting luminosity of L[C II] ∼ (1.6–2.5) × 108 Le. We identify 14 [C II] line emitting candidates in this redshift range with significances >4.5σ, two of which correspond to blind detections with no optical counterparts. At this significance level, our statistical analysis shows that about 60% of our candidates are expected to be spurious. For one of our blindly selected [C II] line candidates, we tentatively detect the CO(6-5) line in our parallel 3 mm line scan. None of the line candidates are individually detected in the 1.2 mm continuum. A stack of all [C II] candidates results in a tentative detection with S1.2 mm = 14 ± 5 μJy. This implies a dust-obscured star-formation rate (SFR) of (3 ± 1) Me yr−1 . We find that the two highest-SFR objects have candidate [C II] lines with luminosities that are consistent with the low-redshift L[C II] versus SFR relation. The other candidates have significantly higher [C II] luminosities than expected from their UV-based SFR. At the current sensitivity, it is unclear whether the majority of these sources are intrinsically bright [C II] emitters, or spurious sources. If only one of our line candidates was real (a scenario greatly favored by our statistical analysis), we find a source density for [C II] emitters at 6 < z < 8 that is significantly higher than predicted by current models and some extrapolations from galaxies in the local universe.