Euclid preparation

V. Predicted yield of redshift 7 < z < 9 quasars from the wide survey

¹ Astrophysics Group, Blackett Laboratory, Imperial College London, London SW7 2AZ, UK
e-mail: rhys.barnett09@imperial.ac.uk
² Department of Astronomy, Stockholm University, Albanova 10691 Stockholm, Sweden
³ Department of Mathematics, Imperial College London, London SW7 2AZ, UK
⁴ Aix-Marseille Univ., CNRS, CNES, LAM, Marseille, France
⁵ University of Nottingham, University Park, Nottingham NG7 2RD, UK
⁶ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
⁷ NRC Herzberg, 5071 West Saanich Rd, Victoria, BC V9E 2E7, Canada
⁸ INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy
⁹ Instituto de Astrofísica de Canarias, Calle Vía Láctea s/n, 38204 San Cristóbal de la Laguna, Tenerife, Spain
¹⁰ Dipartimento di Fisica e Astronomia, Universitá di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy
¹¹ INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
¹² Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany
¹³ Universitäts-Sternwarte München, Fakultät für Physik, Ludwig-Maximilians-Universität München, Scheinerstrasse 1, 81679 München, Germany
¹⁴ INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34131 Trieste, Italy
¹⁵ INAF-Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025 Pino Torinese, TO, Italy
¹⁶ Department of Astronomy, University of Geneva, ch. d’Écogia 16, 1290 Versoix, Switzerland
¹⁷ INFN-Sezione di Roma Tre, Via della Vasca Navale 84, 00146 Roma, Italy
¹⁸ Department of Mathematics and Physics, Roma Tre University, Via della Vasca Navale 84, 00146 Rome, Italy
¹⁹ INAF-Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monteporzio, Catone, Italy
²⁰ INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Napoli, Italy
²¹ Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
²² Dipartimento di Fisica e Scienze della Terra, Universitá degli Studi di Ferrara, Via Giuseppe Saragat 1, 44122 Ferrara, Italy
²³ INAF, Istituto di Radioastronomia, Via Piero Gobetti 101, 40129 Bologna, Italy
²⁴ INFN-Sezione di Torino, Via P. Giuria 1, 10125 Torino, Italy
²⁵ Dipartimento di Fisica, Universitá degli Studi di Torino, Via P. Giuria 1, 10125 Torino, Italy
²⁶ INFN-Sezione di Milano, Via Celoria 16, 20133 Milan, Italy
²⁷ INAF-IASF Milano, Via Alfonso Corti 12, 20133 Milano, Italy
²⁸ Institut de Física d’Altes Energies IFAE, 08193 Bellaterra, Barcelona, Spain
²⁹ Instituto de Astrofísica e Ciências do Espaço, Faculdade de Ciências, Universidade de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal
³⁰ Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans, s/n, 08193 Barcelona, Spain
³¹ Institut d’Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain
³² Department of Physics “E. Pancini”, University Federico II, Via Cinthia 6, 80126 Napoli, Italy
³³ INFN Section of Naples, Via Cinthia 6, 80126 Napoli, Italy
³⁴ INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
³⁵ Centre National d’Etudes Spatiales, Toulouse, France
³⁶ Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
³⁷ ESAC/ESA, Camino Bajo del Castillo, s/n, Urb. Villafranca del Castillo, 28692 Villanueva de la Cañada, Madrid, Spain
³⁸ Université de Lyon, 69622 Lyon, France
³⁹ Université de Lyon 1, Villeurbanne, France
⁴⁰ CNRS/IN2P3, Institut de Physique Nucléaire de Lyon, France
⁴¹ Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK
⁴² Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, Edifício C8, Campo Grande, 1749-016 Lisboa, Portugal
⁴³ Instituto de Astrofísica e Ciências do Espaço, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
⁴⁴ Department of Physics, Oxford University, Keble Road, Oxford OX1 3RH, UK
⁴⁵ INFN-Padova, Via Marzolo 8, 35131 Padova, Italy
⁴⁶ Institut de Physique Nucléaire de Lyon, 4 rue Enrico Fermi, 69622 Villeurbanne Cedex, France
⁴⁷ Aix-Marseille Univ., CNRS/IN2P3, CPPM, Marseille, France
⁴⁸ AIM, CEA, CNRS, Université Paris-Saclay, Université Paris Diderot, Sorbonne Paris Cité, 91191 Gif-sur-Yvette, France
⁴⁹ Institut de Ciencies de l’Espai (IEEC-CSIC), Campus UAB, Carrer de Can Magrans, s/n Cerdanyola del Vallés, 08193 Barcelona, Spain
⁵⁰ Centre for Extragalactic Astronomy, Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
⁵¹ Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
⁵² von Hoerner & Sulger GmbH, SchloßPlatz 8, 68723 Schwetzingen, Germany
⁵³ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
⁵⁴ Institut d’Astrophysique de Paris, 98bis Boulevard Arago, 75014 Paris, France
⁵⁵ Department of Physics and Helsinki Institute of Physics, University of Helsinki, Gustaf Hällströmin katu 2, 00014 Helsinki, Finland
⁵⁶ Université de Genève, Département de Physique Théorique and Centre for Astroparticle Physics, 24 Quai Ernest-Ansermet, 1211 Genève 4, Switzerland
⁵⁷ European Space Agency/ESTEC, Keplerlaan 1, 2201, AZ Noordwijk, The Netherlands
⁵⁸ Institute of Theoretical Astrophysics, University of Oslo, PO Box 1029, Blindern 0315, Oslo, Norway
⁵⁹ Institute of Space Sciences (IEEC-CSIC), c/Can Magrans s/n, 08193 Cerdanyola del Vallés, Barcelona, Spain
⁶⁰ Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
⁶¹ Institute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
⁶² INAF-Osservatorio Astronomico di Padova, Via dell’Osservatorio 5, 35122 Padova, Italy
⁶³ University of Paris Denis Diderot, University of Paris Sorbonne Cité (PSC), 75205 Paris Cedex 13, France
⁶⁴ Sorbonne Université, Observatoire de Paris, Université PSL, CNRS, LERMA, 75014 Paris, France
⁶⁵ CEA Saclay, DFR/IRFU, Service d’Astrophysique, Bât. 709, 91191 Gif-sur-Yvette, France
⁶⁶ INAF-IASF Bologna, Via Piero Gobetti 101, 40129 Bologna, Italy
⁶⁷ Observatoire de Sauverny, Ecole Polytechnique Fédérale de Lau- sanne, 1290 Versoix, Switzerland
⁶⁸ INFN-Bologna, Via Irnerio 46, 40126 Bologna, Italy
⁶⁹ Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands
⁷⁰ Perimeter Institute for Theoretical Physics, Waterloo, ON N2L 2Y5, Canada
⁷¹ Department of Physics and Astronomy, University of Waterloo, Waterloo, ON N2L 3G1, Canada
⁷² Centre for Astrophysics, University of Waterloo, Waterloo, ON N2L 3G1, Canada
⁷³ Space Science Data Center, Italian Space Agency, Via del Politecnico snc, 00133 Roma, Italy
⁷⁴ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
⁷⁵ Departamento de Física, FCFM, Universidad de Chile, Blanco Encalada 2008, Santiago, Chile
⁷⁶ I.N.F.N.-Sezione di Roma Piazzale Aldo Moro, 2 – c/o Dipartimento di Fisica, Edificio G. Marconi, 00185 Roma, Italy
⁷⁷ Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Avenida Complutense 40, 28040 Madrid, Spain
⁷⁸ Phys. Dep. Università di Milano-Bicocca, Piazza della Scienza 3, Milano, Italy
⁷⁹ INFN-Sezione di Milano-Bicocca, Piazza della Scienza 3, 20126 Milan, Italy
⁸⁰ Universidad Politécnica de Cartagena, Departamento de Electrónica y Tecnología de Computadoras, 30202 Cartagena, Spain
⁸¹ Departamento Física Aplicada, Universidad Politécnica de Cartagena, Campus Muralla del Mar, 30202 Cartagena, Murcia, Spain
⁸² Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125, USA

Received: 1 August 2019
Accepted: 16 September 2019

Abstract

We provide predictions of the yield of 7 <  z <  9 quasars from the Euclid wide survey, updating the calculation presented in the Euclid Red Book in several ways. We account for revisions to the Euclid near-infrared filter wavelengths; we adopt steeper rates of decline of the quasar luminosity function (QLF; Φ) with redshift, Φ ∝ 10^{k(z − 6)}, k = −0.72, and a further steeper rate of decline, k = −0.92; we use better models of the contaminating populations (MLT dwarfs and compact early-type galaxies); and we make use of an improved Bayesian selection method, compared to the colour cuts used for the Red Book calculation, allowing the identification of fainter quasars, down to J_AB ∼ 23. Quasars at z >  8 may be selected from Euclid OYJH photometry alone, but selection over the redshift interval 7 <  z <  8 is greatly improved by the addition of z-band data from, e.g., Pan-STARRS and LSST. We calculate predicted quasar yields for the assumed values of the rate of decline of the QLF beyond z = 6. If the decline of the QLF accelerates beyond z = 6, with k = −0.92, Euclid should nevertheless find over 100 quasars with 7.0 <  z <  7.5, and ∼25 quasars beyond the current record of z = 7.5, including ∼8 beyond z = 8.0. The first Euclid quasars at z >  7.5 should be found in the DR1 data release, expected in 2024. It will be possible to determine the bright-end slope of the QLF, 7 <  z <  8, M₁₄₅₀ <  −25, using 8 m class telescopes to confirm candidates, but follow-up with JWST or E-ELT will be required to measure the faint-end slope. Contamination of the candidate lists is predicted to be modest even at J_AB ∼ 23. The precision with which k can be determined over 7 <  z <  8 depends on the value of k, but assuming k = −0.72 it can be measured to a 1σ uncertainty of 0.07.