Accepted author manuscript, 5.67 MB, PDF document
Available under license: CC BY: Creative Commons Attribution 4.0 International License
Submitted manuscript
Licence: CC BY
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - Euclid preparation: XXI. Intermediate-redshift contaminants in the search for z>6 galaxies within the Euclid Deep Survey
AU - Euclid Collaboration
AU - van Mierlo, S. E.
AU - Caputi, K. I.
AU - Ashby, M.
AU - Atek, H.
AU - Bolzonella, M.
AU - Bowler, R. A. A.
AU - Brammer, G.
AU - Conselice, C. J.
AU - Cuby, J.
AU - Dayal, P.
AU - Díaz-Sánchez, A.
AU - Finkelstein, Steven L.
AU - Hoekstra, H.
AU - Humphrey, A.
AU - Ilbert, O.
AU - McCracken, H. J.
AU - Milvang-Jensen, B.
AU - Oesch, P. A.
AU - Pello, R.
AU - Rodighiero, G.
AU - Schirmer, M.
AU - Tof, S.
AU - Weaver, J. R.
AU - Wilkins, S. M.
AU - Willott, C. J.
AU - Zamorani, G.
AU - Amara, A.
AU - Auricchio, N.
AU - Baldi, M.
AU - Bender, R.
AU - Bodendorf, C.
AU - Bonino, D.
AU - Branchini, E.
AU - Brescia, M.
AU - Brinchmann, J.
AU - Camera, S.
AU - Capobianco, V.
AU - Carbone, C.
AU - Carretero, J.
AU - Castellano, M.
AU - Cavuoti, S.
AU - Cimatti, A.
AU - Cledassou, R.
AU - Congedo, G.
AU - Conversi, L.
AU - Copin, Y.
AU - Corcione, L.
AU - Courbin, F.
AU - Hook, I.
PY - 2022/7/18
Y1 - 2022/7/18
N2 - (Abridged) The Euclid mission is expected to discover thousands of z>6 galaxies in three Deep Fields, which together will cover a ~40 deg2 area. However, the limited number of Euclid bands and availability of ancillary data could make the identification of z>6 galaxies challenging. In this work, we assess the degree of contamination by intermediate-redshift galaxies (z=1-5.8) expected for z>6 galaxies within the Euclid Deep Survey. This study is based on ~176,000 real galaxies at z=1-8 in a ~0.7 deg2 area selected from the UltraVISTA ultra-deep survey, and ~96,000 mock galaxies with 25.3$\leq$H<27.0, which altogether cover the range of magnitudes to be probed in the Euclid Deep Survey. We simulate Euclid and ancillary photometry from the fiducial, 28-band photometry, and fit spectral energy distributions (SEDs) to various combinations of these simulated data. Our study demonstrates that identifying z>6 with Euclid data alone will be very effective, with a z>6 recovery of 91(88)% for bright (faint) galaxies. For the UltraVISTA-like bright sample, the percentage of z=1-5.8 contaminants amongst apparent z>6 galaxies as observed with Euclid alone is 18%, which is reduced to 4(13)% by including ultra-deep Rubin (Spitzer) photometry. Conversely, for the faint mock sample, the contamination fraction with Euclid alone is considerably higher at 39%, and minimized to 7% when including ultra-deep Rubin data. For UltraVISTA-like bright galaxies, we find that Euclid (I-Y)>2.8 and (Y-J)<1.4 colour criteria can separate contaminants from true z>6 galaxies, although these are applicable to only 54% of the contaminants, as many have unconstrained (I-Y) colours. In the most optimistic scenario, these cuts reduce the contamination fraction to 1% whilst preserving 81% of the fiducial z>6 sample. For the faint mock sample, colour cuts are infeasible....
AB - (Abridged) The Euclid mission is expected to discover thousands of z>6 galaxies in three Deep Fields, which together will cover a ~40 deg2 area. However, the limited number of Euclid bands and availability of ancillary data could make the identification of z>6 galaxies challenging. In this work, we assess the degree of contamination by intermediate-redshift galaxies (z=1-5.8) expected for z>6 galaxies within the Euclid Deep Survey. This study is based on ~176,000 real galaxies at z=1-8 in a ~0.7 deg2 area selected from the UltraVISTA ultra-deep survey, and ~96,000 mock galaxies with 25.3$\leq$H<27.0, which altogether cover the range of magnitudes to be probed in the Euclid Deep Survey. We simulate Euclid and ancillary photometry from the fiducial, 28-band photometry, and fit spectral energy distributions (SEDs) to various combinations of these simulated data. Our study demonstrates that identifying z>6 with Euclid data alone will be very effective, with a z>6 recovery of 91(88)% for bright (faint) galaxies. For the UltraVISTA-like bright sample, the percentage of z=1-5.8 contaminants amongst apparent z>6 galaxies as observed with Euclid alone is 18%, which is reduced to 4(13)% by including ultra-deep Rubin (Spitzer) photometry. Conversely, for the faint mock sample, the contamination fraction with Euclid alone is considerably higher at 39%, and minimized to 7% when including ultra-deep Rubin data. For UltraVISTA-like bright galaxies, we find that Euclid (I-Y)>2.8 and (Y-J)<1.4 colour criteria can separate contaminants from true z>6 galaxies, although these are applicable to only 54% of the contaminants, as many have unconstrained (I-Y) colours. In the most optimistic scenario, these cuts reduce the contamination fraction to 1% whilst preserving 81% of the fiducial z>6 sample. For the faint mock sample, colour cuts are infeasible....
M3 - Journal article
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
SN - 1432-0746
ER -