Bouwens, RJ, Oesch, PA, Labbe, I, Illingworth, GD, Fazio, GG, Coe, D, Holwerda, B, Smit, R, Stefanon, M, van Dokkum, PG, Trenti, M, Ashby, MLN, Huang, J-S, Spitler, L, Straatman, C, Bradley, L and Magee, D (2016) THE BRIGHT END OF THE z similar to 9 AND z similar to 10 UV LUMINOSITY FUNCTIONS USING ALL FIVE CANDELS FIELDS. Astrophysical Journal, 830 (2). ISSN 0004-637X

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Abstract

The deep, wide-area (~800–900 arcmin2) near-infrared/WFC3/IR + Spitzer/IRAC observations over the CANDELS fields have been a remarkable resource for constraining the bright end of high-redshift UV luminosity functions. However, the lack of Hubble Space Telescope (HST) 1.05 μm observations over the CANDELS fields has made it difficult to identify z ~ 9–10 sources robustly, since such data are needed to confirm the presence of an abrupt Lyman break at 1.2 μm. Here, we report on the successful identification of many such z ~ 9–10 sources from a new HST program (z9-CANDELS) that targets the highest-probability z ~ 9–10 galaxy candidates with observations at 1.05 μm, to search for a robust Lyman-break at 1.2 μm. The potential z ~ 9–10 candidates were preselected from the full HST, Spitzer/IRAC S-CANDELS observations, and the deepest-available ground-based optical+near-infrared observations (CFHTLS-DEEP+HUGS+UltraVISTA+ZFOURGE). We identified 15 credible z ~ 9–10 galaxies over the CANDELS fields. Nine of these galaxies lie at z ~ 9 and five are new identifications. Our targeted follow-up strategy has proven to be very efficient in making use of scarce HST time to secure a reliable sample of z ~ 9–10 galaxies. Through extensive simulations, we replicate the selection process for our sample (both the preselection and follow-up) and use it to improve current estimates for the volume density of bright z ~ 9 and z ~ 10 galaxies. The volume densities we find are 5${}_{-2}^{+3}\times $ and ${8}_{-3}^{+9}\times $ lower, respectively, than those found at z ~ 8. When compared with the best-fit evolution (i.e., $d\,{\mathrm{log}}_{10}\,{\rho }_{\mathrm{UV}}/{dz}=-0.29\pm 0.02$) in the UV luminosity densities from z ~ 8 to z ~ 4 integrated to $0.3{L}_{z=3}^{* }$ (−20 mag), these luminosity densities are ${2.6}_{-0.9}^{+1.5}\times $ and ${2.2}_{-1.1}^{+2.0}\times $ lower, respectively, than the extrapolated trends. Our new results are broadly consistent with the "accelerated evolution" scenario at z > 8, consistent with that seen in many models.

Item Type:	Article
Uncontrolled Keywords:	Science & Technology; Physical Sciences; Astronomy & Astrophysics; galaxies: formation; galaxies: high-redshift; ULTRA-DEEP FIELD; HUBBLE-SPACE-TELESCOPE; STAR-FORMATION RATE; FORMATION RATE DENSITY; EARLY RELEASE SCIENCE; LYMAN-BREAK GALAXIES; EXTRAGALACTIC LEGACY SURVEY; HIGH-REDSHIFT GALAXIES; SURVEY. SURVEY DESIGN; IRAC SOURCE COUNTS; Science & Technology; Physical Sciences; Astronomy & Astrophysics; galaxies: formation; galaxies: high-redshift; ULTRA-DEEP FIELD; HUBBLE-SPACE-TELESCOPE; STAR-FORMATION RATE; FORMATION RATE DENSITY; EARLY RELEASE SCIENCE; LYMAN-BREAK GALAXIES; EXTRAGALACTIC LEGACY SURVEY; HIGH-REDSHIFT GALAXIES; SURVEY. SURVEY DESIGN; IRAC SOURCE COUNTS; astro-ph.GA; astro-ph.GA; 0201 Astronomical and Space Sciences; 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics; 0306 Physical Chemistry (incl. Structural); Astronomy & Astrophysics
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Divisions:	Astrophysics Research Institute
Publisher:	American Astronomical Society; IOP Publishing
SWORD Depositor:	A Symplectic
Date Deposited:	16 Nov 2022 10:29
Last Modified:	16 Nov 2022 10:30
DOI or ID number:	10.3847/0004-637X/830/2/67
URI:	https://researchonline.ljmu.ac.uk/id/eprint/18143

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