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25. Euclid preparation: VIII. The Complete Calibration of the Colour–Redshift Relation survey: VLT/KMOS observations and data release.

Author

Euclid Collaboration, Guglielmo, V., Saglia, R., Castander, F. J., Galametz, A., Paltani, S., Bender, R., Bolzonella, M., Capak, P., Ilbert, O., Masters, D. C., Stern, D., Andreon, S., Auricchio, N., Balaguera-Antolínez, A., Baldi, M., Bardelli, S., Biviano, A., Bodendorf, C., and Bonino, D.

Subjects
STELLAR mass, DARK energy, GRID cells, CALIBRATION, PHYSICAL cosmology
Abstract

The Complete Calibration of the Colour–Redshift Relation survey (C3R2) is a spectroscopic effort involving ESO and Keck facilities designed specifically to empirically calibrate the galaxy colour–redshift relation – P(z|C) to the Euclid depth (iAB = 24.5) and is intimately linked to the success of upcoming Stage IV dark energy missions based on weak lensing cosmology. The aim is to build a spectroscopic calibration sample that is as representative as possible of the galaxies of the Euclid weak lensing sample. In order to minimise the number of spectroscopic observations necessary to fill the gaps in current knowledge of the P(z|C), self-organising map (SOM) representations of the galaxy colour space have been constructed. Here we present the first results of an ESO@VLT Large Programme approved in the context of C3R2, which makes use of the two VLT optical and near-infrared multi-object spectrographs, FORS2 and KMOS. This data release paper focuses on high-quality spectroscopic redshifts of high-redshift galaxies observed with the KMOS spectrograph in the near-infrared H- and K-bands. A total of 424 highly-reliable redshifts are measured in the 1.3 ≤ z ≤ 2.5 range, with total success rates of 60.7% in the H-band and 32.8% in the K-band. The newly determined redshifts fill 55% of high (mainly regions with no spectroscopic measurements) and 35% of lower (regions with low-resolution/low-quality spectroscopic measurements) priority empty SOM grid cells. We measured Hα fluxes in a 1.″2 1. ″ 2 $ 1{{\overset{\prime\prime}{.}}}2 $ radius aperture from the spectra of the spectroscopically confirmed galaxies and converted them into star formation rates. In addition, we performed an SED fitting analysis on the same sample in order to derive stellar masses, E(B − V), total magnitudes, and SFRs. We combine the results obtained from the spectra with those derived via SED fitting, and we show that the spectroscopic failures come from either weakly star-forming galaxies (at z <  1.7, i.e. in the H-band) or low S/N spectra (in the K-band) of z >  2 galaxies. [ABSTRACT FROM AUTHOR]

Published
2020
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26. horizon-AGN virtual observatory – 2. Template-free estimates of galaxy properties from colours.

Author

Davidzon, I, Laigle, C, Capak, P L, Ilbert, O, Masters, D C, Hemmati, S, Apostolakos, N, Coupon, J, de la Torre, S, Devriendt, J, Dubois, Y, Kashino, D, Paltani, S, and Pichon, C

Subjects
GALAXY formation, GALAXY spectra, GALAXIES, STELLAR mass, SELF-organizing maps, SEYFERT galaxies
Abstract

Using the horizon-AGN hydrodynamical simulation and self-organizing maps (SOMs), we show how to compress the complex, high-dimensional data structure of a simulation into a 2D grid, which greatly facilitates the analysis of how galaxy observables are connected to intrinsic properties. We first verify the tight correlation between the observed 0.3–5  μ m broad-band colours of horizon-AGN galaxies and their high-resolution spectra. The correlation is found to extend to physical properties such as redshift, stellar mass, and star formation rate (SFR). This direct mapping from colour to physical parameter space still works after including photometric uncertainties that mimic the COSMOS survey. We then label the SOM grid with a simulated calibration sample to estimate redshift and SFR for COSMOS-like galaxies up to z ∼ 3. In comparison to state-of-the-art techniques based on synthetic templates, our method is comparable in performance but less biased at estimating redshifts, and significantly better at predicting SFRs. In particular, our 'data-driven' approach, in contrast to model libraries, intrinsically allows for the complexity of galaxy formation and can handle sample biases. We advocate that observations to calibrate this method should be one of the goals of next-generation galaxy surveys. [ABSTRACT FROM AUTHOR]

Published
2019
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27. Phenotypic redshifts with self-organizing maps: A novel method to characterize redshift distributions of source galaxies for weak lensing.

Author

Buchs, R, Davis, C, Gruen, D, DeRose, J, Alarcon, A, Bernstein, G M, Sánchez, C, Myles, J, Roodman, A, Allen, S, Amon, A, Choi, A, Masters, D C, Miquel, R, Troxel, M A, Wechsler, R H, Abbott, T M C, Annis, J, Avila, S, and Bechtol, K

Subjects
SELF-organizing maps, SPECTRAL energy distribution, DARK energy, GALAXIES, GALAXY clusters, REDSHIFT
Abstract

Wide-field imaging surveys such as the Dark Energy Survey (DES) rely on coarse measurements of spectral energy distributions in a few filters to estimate the redshift distribution of source galaxies. In this regime, sample variance, shot noise, and selection effects limit the attainable accuracy of redshift calibration and thus of cosmological constraints. We present a new method to combine wide-field, few-filter measurements with catalogues from deep fields with additional filters and sufficiently low photometric noise to break degeneracies in photometric redshifts. The multiband deep field is used as an intermediary between wide-field observations and accurate redshifts, greatly reducing sample variance, shot noise, and selection effects. Our implementation of the method uses self-organizing maps to group galaxies into phenotypes based on their observed fluxes, and is tested using a mock DES catalogue created from N -body simulations. It yields a typical uncertainty on the mean redshift in each of five tomographic bins for an idealized simulation of the DES Year 3 weak-lensing tomographic analysis of σΔ z = 0.007, which is a 60 per cent improvement compared to the Year 1 analysis. Although the implementation of the method is tailored to DES, its formalism can be applied to other large photometric surveys with a similar observing strategy. [ABSTRACT FROM AUTHOR]

Published
2019
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40. Euclid: the selection of quiescent and star-forming galaxies using observed colours

Author

F. J. Castander, Rafael Toledo-Moreo, L. Bisigello, Marc Sauvage, M. Poncet, Ulrike Kuchner, H. Israel, R. Cledassou, S. Kermiche, Crescenzo Tortora, F. Sureau, Sebastiano Ligori, R. Kohley, Sandrine Pires, Jarle Brinchmann, Mauro Roncarelli, Michele Moresco, G. Zamorani, Andy Taylor, G. Meylan, Andrea Cimatti, Natalia Auricchio, J. Carretero, B. Kubik, M. Wetzstein, Lucia Pozzetti, Thomas D. Kitching, Felix Hormuth, Stefano Andreon, E. Franceschi, Claudia Maraston, M. Bolzonella, Roberto P. Saglia, Martin Kunz, Simona Mei, D. Masters, M. Frailis, Andrew Humphrey, Leonardo Corcione, A. Secroun, Mark Cropper, Ismael Tereno, G. Polenta, V. Capobianco, Jason Rhodes, L. Valenziano, Ivan Lloro, S. Serrano, Peter Schneider, Elisabetta Maiorano, L. Conversi, Fabio Pasian, Ole Marggraf, G. Congedo, P. B. Lilje, S. Dusini, S. Paltani, Y. Mellier, Valeria Pettorino, P. Franzetti, C. J. Conselice, F. Raison, B. Garilli, Yu Wang, Marco Castellano, M. Fumana, O. Le Fevre, Richard Massey, Knud Jahnke, Pierre-Alain Duc, Stefano Cavuoti, Emanuel Rossetti, C. Padilla, Julien Zoubian, Zoubian, J, Wetzstein, M, Wang, Y, Valenziano, L, Toledo-Moreo, R, Tereno, I, Taylor, A N, Sureau, F, Serrano, S, Secroun, A, Schneider, P, Sauvage, M, Saglia, R, Rossetti, E, Roncarelli, M, Rhodes, J, Raison, F, Poncet, M, Polenta, G, Pires, S, Pettorino, V, Pasian, F, Paltani, S, Padilla, C, Meylan, G, Mellier, Y, Mei, S, Masters, D C, Massey, R, Marggraf, O, Maiorano, E, Lloro, I, Lilje, P B, Ligori, S, Le Fèvre, O, Kunz, M, Kubik, B, Kohley, R, Kitching, T, Kermiche, S, Jahnke, K, Israel, H, Hormuth, F, Fumana, M, Franzetti, P, Franceschi, E, Frailis, M, Dusini, S, Cropper, M S, Corcione, L, Conversi, L, Congedo, G, Cledassou, R, Cimatti, A, Cavuoti, S, Castellano, M, Castander, F J, Carretero, J, Capobianco, V, Brinchmann, J, Auricchio, N, Zamorani, G, Tortora, C, Pozzetti, L, Moresco, M, Maraston, C, Humphrey, A, Garilli, B, Duc, P-A, Bolzonella, M, Andreon, S, Conselice, C J, Kuchner, U, Bisigello, L, Observatoire astronomique de Strasbourg (ObAS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National d'Études Spatiales [Toulouse] (CNES), Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Université Paris Diderot - Paris 7 (UPD7), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)

Subjects
photometric redshifts, challenge lightcone simulation, Sample (material), FOS: Physical sciences, Astrophysics, Star (graph theory), 01 natural sciences, law.invention, Telescope, environmental dependence, law, 0103 physical sciences, Galaxy formation and evolution, formation rates, luminosity function, 010303 astronomy & astrophysics, Physics, 010308 nuclear & particles physics, Astronomy and Astrophysics, legacy survey, evolution survey cosmos, Astrophysics - Astrophysics of Galaxies, galaxies: general, red sequence, Galaxy, Redshift, galaxies: photometry, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), magnitude distribution, stellar mass, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], galaxies: evolution
Abstract

The Euclid mission will observe well over a billion galaxies out to $z\sim6$ and beyond. This will offer an unrivalled opportunity to investigate several key questions for understanding galaxy formation and evolution. The first step for many of these studies will be the selection of a sample of quiescent and star-forming galaxies, as is often done in the literature by using well known colour techniques such as the `UVJ' diagram. However, given the limited number of filters available for the Euclid telescope, the recovery of such rest-frame colours will be challenging. We therefore investigate the use of observed Euclid colours, on their own and together with ground-based u-band observations, for selecting quiescent and star-forming galaxies. The most efficient colour combination, among the ones tested in this work, consists of the (u-VIS) and (VIS-J) colours. We find that this combination allows users to select a sample of quiescent galaxies complete to above $\sim70\%$ and with less than 15$\%$ contamination at redshifts in the range $0.7565\%$ completeness level and contamination below 20$\%$ at $1, Comment: 19 pages, 15 figures, 5 tables, accepted for publication in MNRAS

Published
2020
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