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

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....

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 OY JH 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.

Citation

Barnett, R., Warren, S., Mortlock, D., Cuby, J.-G., Conselice, C., Hewett, P., Willott, C., 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., …Zucca, E. (2019). Euclid preparation: V. Predicted yield of redshift 7 < z < 9 quasars from the wide survey. Astronomy & Astrophysics, 631, Article A85. https://doi.org/10.1051/0004-6361/201936427

• Journal Article Type: Article
• Online Publication Date: Oct 25, 2019
• Publication Date: 2019-11
• Deposit Date: Oct 21, 2020
• Publicly Available Date: Oct 21, 2020
• Journal: Astronomy and astrophysics.
• Print ISSN: 0004-6361
• Electronic ISSN: 1432-0746
• Publisher: EDP Sciences
• Peer Reviewed: Peer Reviewed
• Volume: 631
• Article Number: A85
• DOI: https://doi.org/10.1051/0004-6361/201936427
• Public URL: https://durham-repository.worktribe.com/output/1289012