TY - JOUR

T1 - Euclid preparation

T2 - V. Predicted yield of redshift 7

AU - Euclid Collaboration

AU - Collaboration, Euclid

AU - Barnett, R.

AU - Warren, S. J.

AU - Mortlock, D. J.

AU - Cuby, J. -G.

AU - Conselice, C.

AU - Hewett, P. C.

AU - Willott, C. J.

AU - Auricchio, N.

AU - Balaguera-Antolínez, A.

AU - Baldi, M.

AU - Bardelli, S.

AU - Bellagamba, F.

AU - Bender, R.

AU - Biviano, A.

AU - Bonino, D.

AU - Bozzo, E.

AU - Branchini, E.

AU - Brescia, M.

AU - Brinchmann, J.

AU - Burigana, C.

AU - Camera, S.

AU - Capobianco, V.

AU - Carbone, C.

AU - Carretero, J.

AU - Carvalho, C. S.

AU - Castander, F. J.

AU - Castellano, M.

AU - Cavuoti, S.

AU - Cimatti, A.

AU - Clédassou, R.

AU - Congedo, G.

AU - Conversi, L.

AU - Copin, Y.

AU - Corcione, L.

AU - Coupon, J.

AU - Courtois, H. M.

AU - Cropper, M.

AU - Silva, A. Da

AU - Duncan, C. A. J.

AU - Dusini, S.

AU - Gillis, B. R.

AU - Israel, H.

AU - Kitching, T.

AU - Massey, R.

AU - Percival, W. J.

AU - Rhodes, J.

AU - Schneider, P.

AU - Taylor, A. N.

AU - Wang, Y.

N1 - Published in A&A. Updated to match accepted version

PY - 2019/11/1

Y1 - 2019/11/1

N2 - 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.

AB - 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.

KW - astro-ph.GA

KW - astro-ph.CO

U2 - 10.1051/0004-6361/201936427

DO - 10.1051/0004-6361/201936427

M3 - Article

VL - 631

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

M1 - A85

ER -