Title: The PAU Survey: an improved photo-z sample in the COSMOS field

Abstract

Here we present – and make publicly available – accurate and precise photometric redshifts in the ACS footprint from the COSMOS field for objects with i_AB ≤ 23. The redshifts are computed using a combination of narrow-band photometry from PAUS, a survey with 40 narrow bands spaced at $$100\,\mathring{\rm A}$$ intervals covering the range from 4500 to $$8500\,\mathring{\rm A}$$, and 26 broad, intermediate, and narrow bands covering the UV, visible and near-infrared spectrum from the COSMOS2015 catalogue. We introduce a new method that models the spectral energy distributions as a linear combination of continuum and emission-line templates and computes its Bayes evidence, integrating over the linear combinations. The correlation between the UV luminosity and the $$\mathrm{O\,{\small II}}$$ line is measured using the 66 available bands with the zCOSMOS spectroscopic sample, and used as a prior which constrains the relative flux between continuum and emission-line templates. The flux ratios between the $$\mathrm{O\,{\small II}}$$ line and H_α, H_β and $$\mathrm{O\,{\small III}}$$ are similarly measured and used to generate the emission-line templates. Comparing to public spectroscopic surveys via the quantity Δ_z ≡ (z_photo – z_spec)/(1 + z_spec), we find the photometric redshifts to be more precise than previous estimates, with σ₆₈(Δ_z) ≈ (0.003, 0.009) for galaxies at magnitude i_AB ~ 18 and i_AB ~ 23, respectively, which is three times and 1.66 times tighter than COSMOS2015. Additionally, we find the redshifts to be very accurate on average, yielding a median of the Δ_z distribution compatible with |median(Δ_z)| ≤ 0.001 at all redshifts and magnitudes considered. Both the added PAUS data and new methodology contribute significantly to the improved results. The catalogue produced with the technique presented here is expected to provide a robust redshift calibration for current and future lensing surveys, and allows one to probe galaxy formation physics in an unexplored luminosity-redshift regime, thanks to its combination of depth, completeness, and excellent redshift precision and accuracy.

Authors:

Alarcon, Alex  ^[1];

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Gaztanaga, Enrique  ^[2];

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Eriksen, Martin ^[3]; Baugh, Carlton M. ^[4]; Cabayol, Laura ^[3]; Casas, Ricard ^[2]; Carretero, Jorge ^[3]; Castander, Francisco J. ^[2]; De Vicente, Juan ^[5]; Fernandez, Enrique ^[3]; Garcia-Bellido, Juan  ^[6];

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Hildebrandt, Hendrik ^[7]; Hoekstra, Henk  ^[8];

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Joachimi, Benjamin ^[9]; Manzoni, Giorgio  ^[10];

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Miquel, Ramon ^[11]; Norberg, Peder ^[10]; Padilla, Cristobal ^[3]; Renard, Pablo  ^[2];

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Sanchez, Eusebio ^[5] more »; Serrano, Santiago ^[2]; Sevilla-Noarbe, Ignacio ^[5]; Siudek, Malgorzata  ^[3];

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Tallada-Crespí, Pau ^[5] « less

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1. HEP Division, Argonne National Laboratory, Lemont, IL 60439, USA, Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans, s/n, E-08193 Barcelona, Spain, Institut d’Estudis Espacials de Catalunya (IEEC), E-08034 Barcelona, Spain
2. Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans, s/n, E-08193 Barcelona, Spain, Institut d’Estudis Espacials de Catalunya (IEEC), E-08034 Barcelona, Spain
3. Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, E-08193 Bellaterra (Barcelona), Spain
4. Institute for Computational Cosmology (ICC), Department of Physics, Durham University, South Road, Durham DH1 3LE, UK, Institute for Data Science (IDAS), Durham University, South Road, Durham DH1 3LE, UK
5. CIEMAT, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, Avda. Complutenes 40, E-28040 Madrid, Spain
6. Instituto de Fisica Teorica (IFT-UAM/CSIC), Universidad Autonoma de Madrid, E-28049 Madrid, Spain
7. Ruhr-University Bochum, Astronomical Institute, German Centre for Cosmological Lensing, Universitätsstr. 150, D-44801 Bochum, Germany
8. Leiden Observatory, Leiden University, Niels Bohrweg 2, NL-2333 CA Leiden, the Netherlands
9. Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
10. Institute for Computational Cosmology (ICC), Department of Physics, Durham University, South Road, Durham DH1 3LE, UK, Institute for Data Science (IDAS), Durham University, South Road, Durham DH1 3LE, UK, Centre for Extragalactic Astronomy (CEA), Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
11. Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, E-08193 Bellaterra (Barcelona), Spain, Institució Catalana de Recerca i Estudis Avançats (ICREA), E-08010 Barcelona, Spain

Publication Date:

Fri Jan 22 00:00:00 EST 2021

Research Org.:

Argonne National Laboratory (ANL), Argonne, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC), High Energy Physics (HEP); Ministry of Economic Affairs and Digital Transformation of Spain (MINECO); European Regional Development Fund (ERDF); Generalitat de Catalunya; Netherlands Organization for Scientific Research (NWO); European Union’s Horizon 2020; German Research Foundation (DFG); National Science Centre of Poland (NCN); Ministry of Science and Innovation

OSTI Identifier:

1763442

Alternate Identifier(s):

OSTI ID: 1765162

Grant/Contract Number:  

AC02-06CH11357; CSD2007-00060; AYA2015-71825; ESP2017-89838; PGC2018-094773; PGC2018-102021; SEV-2016-0588; SEV-2016-0597; MDM-2015-0509; 734374; 776247; 639.043.512; Hi 1495/5-1; 770935; 754510; UMO-2016/23/N/ST9/02963

Resource Type:

Published Article

Journal Name:

Monthly Notices of the Royal Astronomical Society

Additional Journal Information:

Journal Name: Monthly Notices of the Royal Astronomical Society Journal Volume: 501 Journal Issue: 4; Journal ID: ISSN 0035-8711

Publisher:

Royal Astronomical Society

Country of Publication:

United Kingdom

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS; cosmology; galaxy evolution; photometric redshifts