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

R. Barnett * S. J. Warren D. J. Mortlock J.-G. Cuby 1 C. Conselice P. C. Hewett C. J. Willott N. Auricchio A. Balaguera-Antolínez M. Baldi S. Bardelli F. Bellagamba R. Bender A. Biviano 2 D. Bonino E. Bozzo E. Branchini 3 M. Brescia J. Brinchmann C. Burigana S. Camera V. Capobianco C. Carbone 4 J. Carretero C. S. Carvalho 5, 6 F. J. Castander M. Castellano S. Cavuoti A. Cimatti 7 R. Clédassou 8 G. Congedo L. Conversi Y. Copin 9 L. Corcione J. Coupon H. M. Courtois 9 M. Cropper 10 A. da Silva C. A. J. Duncan S. Dusini A. Ealet 11, 9 S. Farrens 12 P. Fosalba S. Fotopoulou N. Fourmanoit 11 M. Frailis M. Fumana S. Galeotta B. Garilli 13 W. Gillard 11 B. R. Gillis 14 J. Graciá-Carpio 15 F. Grupp H. Hoekstra F. Hormuth H. Israel K. Jahnke S. Kermiche 11 M. Kilbinger 16 C. C. Kirkpatrick 17 T. Kitching R. Kohley B. Kubik 18 M. Kunz H. Kurki-Suonio 19 R. Laureijs S. Ligori P. B. Lilje I. Lloro E. Maiorano O. Mansutti O. Marggraf N. Martinet 20 F. Marulli 21 R. Massey N. Mauri E. Medinaceli S. Mei 22 Y. Mellier 23 R. B. Metcalf J. J. Metge 8 G. Meylan M. Moresco 24 L. Moscardini E. Munari C. Neissner S. M. Niemi T. Nutma C. Padilla S. Paltani F. Pasian P. Paykari 10 W. J. Percival 25 V. Pettorino 26 G. Polenta 27 M. Poncet 8 L. Pozzetti 28 F. Raison A. Renzi J. Rhodes H.-W. Rix E. Romelli M. Roncarelli E. Rossetti 29 R. Saglia D. Sapone R. Scaramella P. Schneider 30 V. Scottez 31 A. Secroun 11 S. Serrano G. Sirri L. Stanco F. Sureau 26 P. Tallada-Crespí D. Tavagnacco 2 A. N. Taylor 32 M. Tenti I. Tereno R. Toledo-Moreo F. Torradeflot L. Valenziano 33 T. Vassallo 34 Y. Wang 35 A. Zacchei G. Zamorani J. Zoubian 11 E. Zucca 36 
* Corresponding author
6 SEN - Sénescence et stabilité génomique
DBG - Département Biologie des Génomes
35 Continental Dynamics Laboratory [CAGS Beijing]
CAGS - Institute of Geology [CAGS Beijing]
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; $\Phi$) with redshift, $\Phi$ ∝ 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 $J_{AB}$ $\sim$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 $\sim$25 quasars beyond the current record of z = 7.5, including $\sim$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, $M_{1450}$ <  −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}$$\sim$ 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 1$\sigma$ uncertainty of 0.07.
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R. Barnett, S. J. Warren, D. J. Mortlock, J.-G. Cuby, C. Conselice, et al.. Euclid preparation: V. Predicted yield of redshift 7 < z < 9 quasars from the wide survey. Astronomy and Astrophysics - A&A, EDP Sciences, 2019, 631, pp.A85. ⟨10.1051/0004-6361/201936427⟩. ⟨cea-02334278⟩



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