Author:
,Barnett R.,Warren S. J.,Mortlock D. J.,Cuby J.-G.,Conselice C.,Hewett P. C.,Willott C. J.,Auricchio N.,Balaguera-Antolínez A.,Baldi M.,Bardelli S.,Bellagamba F.,Bender R.,Biviano A.,Bonino D.,Bozzo E.,Branchini E.,Brescia M.,Brinchmann J.,Burigana C.,Camera S.,Capobianco V.,Carbone C.,Carretero J.,Carvalho C. S.,Castander F. J.,Castellano M.,Cavuoti S.,Cimatti A.,Clédassou R.,Congedo G.,Conversi L.,Copin Y.,Corcione L.,Coupon J.,Courtois H. M.,Cropper M.,Da Silva A.,Duncan C. A. J.,Dusini S.,Ealet A.,Farrens S.,Fosalba P.,Fotopoulou S.,Fourmanoit N.,Frailis M.,Fumana M.,Galeotta S.,Garilli B.,Gillard W.,Gillis B. R.,Graciá-Carpio J.,Grupp F.,Hoekstra H.,Hormuth F.,Israel H.,Jahnke K.,Kermiche S.,Kilbinger M.,Kirkpatrick C. C.,Kitching T.,Kohley R.,Kubik B.,Kunz M.,Kurki-Suonio H.,Laureijs R.,Ligori S.,Lilje P. B.,Lloro I.,Maiorano E.,Mansutti O.,Marggraf O.,Martinet N.,Marulli F.,Massey R.,Mauri N.,Medinaceli E.,Mei S.,Mellier Y.,Metcalf R. B.,Metge J. J.,Meylan G.,Moresco M.,Moscardini L.,Munari E.,Neissner C.,Niemi S. M.,Nutma T.,Padilla C.,Paltani S.,Pasian F.,Paykari P.,Percival W. J.,Pettorino V.,Polenta G.,Poncet M.,Pozzetti L.,Raison F.,Renzi A.,Rhodes J.,Rix H.-W.,Romelli E.,Roncarelli M.,Rossetti E.,Saglia R.,Sapone D.,Scaramella R.,Schneider P.,Scottez V.,Secroun A.,Serrano S.,Sirri G.,Stanco L.,Sureau F.,Tallada-Crespí P.,Tavagnacco D.,Taylor A. N.,Tenti M.,Tereno I.,Toledo-Moreo R.,Torradeflot F.,Valenziano L.,Vassallo T.,Wang Y.,Zacchei A.,Zamorani G.,Zoubian J.,Zucca E.
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 ∝ 10k(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 JAB ∼ 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 JAB ∼ 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.
Subject
Space and Planetary Science,Astronomy and Astrophysics