TY - JOUR

T1 - COSMOS2020

T2 - UV-selected galaxies at z >= 7.5

AU - Kauffmann, O. B.

AU - Ilbert, O.

AU - Weaver, J. R.

AU - McCracken, H. J.

AU - Milvang-Jensen, B.

AU - Brammer, G.

AU - Davidzon, I.

AU - Le Fevre, O.

AU - Liu, D.

AU - Mobasher, B.

AU - Moneti, A.

AU - Shuntov, M.

AU - Toft, S.

AU - Casey, C. M.

AU - Dunlop, J. S.

AU - Kartaltepe, J. S.

AU - Koekemoer, A. M.

AU - Sanders, D. B.

AU - Tresse, L.

PY - 2022/11/7

Y1 - 2022/11/7

N2 - This paper presents a new search for z >= 7.5 galaxies using the COSMOS2020 photometric catalogues. Finding galaxies at the reionisation epoch through deep imaging surveys remains observationally challenging. The larger area covered by ground-based surveys such as COSMOS enables the discovery of the brightest galaxies at these high redshifts. Covering 1.4 deg(2), our COSMOS catalogues were constructed from the latest UltraVISTA data release (DR4) combined with the final Spitzer/IRAC COSMOS images and the Hyper-Suprime-Cam Subaru Strategic Program DR2 release. We identified 17 new 7.5 < z < 10 candidate sources, and confirm 15 previously published candidates. Using deblended photometry extracted by fitting surface brightness models on multi-band images, we selected four candidates which would be rejected using fixed aperture photometry. We tested the robustness of all our candidates by comparing six different photometric redshift estimates. Finally, we computed the galaxy UV luminosity function in three redshift bins centred at z = 8, 9, 10. We find no clear evolution of the number density of the brightest galaxies M-UV < 21 .5, in agreement with previous works. Rapid changes in the quenching efficiency or attenuation by dust could explain such a lack of evolution between z similar to 8 and z similar to 9. A spectroscopic confirmation of the redshifts, already planned with JWST and the Keck telescopes, will be essential to confirm our results.

AB - This paper presents a new search for z >= 7.5 galaxies using the COSMOS2020 photometric catalogues. Finding galaxies at the reionisation epoch through deep imaging surveys remains observationally challenging. The larger area covered by ground-based surveys such as COSMOS enables the discovery of the brightest galaxies at these high redshifts. Covering 1.4 deg(2), our COSMOS catalogues were constructed from the latest UltraVISTA data release (DR4) combined with the final Spitzer/IRAC COSMOS images and the Hyper-Suprime-Cam Subaru Strategic Program DR2 release. We identified 17 new 7.5 < z < 10 candidate sources, and confirm 15 previously published candidates. Using deblended photometry extracted by fitting surface brightness models on multi-band images, we selected four candidates which would be rejected using fixed aperture photometry. We tested the robustness of all our candidates by comparing six different photometric redshift estimates. Finally, we computed the galaxy UV luminosity function in three redshift bins centred at z = 8, 9, 10. We find no clear evolution of the number density of the brightest galaxies M-UV < 21 .5, in agreement with previous works. Rapid changes in the quenching efficiency or attenuation by dust could explain such a lack of evolution between z similar to 8 and z similar to 9. A spectroscopic confirmation of the redshifts, already planned with JWST and the Keck telescopes, will be essential to confirm our results.

KW - galaxies: luminosity function, mass function

KW - galaxies: evolution

KW - galaxies: formation

KW - galaxies: high-redshift

KW - galaxies: photometry

KW - galaxies: statistics

KW - STELLAR POPULATION SYNTHESIS

KW - EVOLUTION SURVEY COSMOS

KW - HUBBLE FRONTIER FIELDS

KW - DIGITAL SKY SURVEY

KW - LUMINOSITY FUNCTION

KW - HIGH-REDSHIFT

KW - BRIGHT END

KW - BLACK-HOLES

KW - DEEP SURVEY

KW - LY-ALPHA

U2 - 10.1051/0004-6361/202243088

DO - 10.1051/0004-6361/202243088

M3 - Journal article

VL - 667

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

SN - 0004-6361

M1 - A65

ER -