A steep decline in the galaxy space density beyond redshift 9 in the CANUCS UV luminosity function

• DOI: 10.48550/arxiv.2311.12234
• Publication Date: 2024-04-26
• Authors: Chris J. Willott; Guillaume Desprez; Yoshihisa Asada; Ghassan T. E. Sar...; Roberto Abraham; Maruša Bradač; Gabe Brammer; Vince Estrada-Car...; Kartheik G. Iyer; Nicholas S. Martis; Jasleen Matharu; Lamiya Mowla; Adam Muzzin; Gaël Noirot; Marcin Sawicki; Victoria Strait; Gregor Rihtaršič; Sunna Withers
• Keywords: high-redshift galaxies, astrophysics of galaxies; FOS: Physical sciences; astrophysics of galaxies; Astrophysics; Astrophysics - Astrophysics of Galaxies; 01 natural sciences; info:eu-repo/classification/udc/524; QB460-466; info:eu-repo/classification/udc/524.8; Astrophysics of Galaxies (astro-ph.GA); 0103 physical sciences; High-redshift galaxies; high-redshift galaxies

Abstract We present a new sample of 158 galaxies at redshift z > 7.5 selected from deep James Webb Space Telescope (JWST) NIRCam imaging of five widely separated sight lines in the CANUCS survey. Two-thirds of the pointings and 80% of the galaxies are covered by 12–14 NIRCam filters, including seven to nine medium bands, providing accurate photometric redshifts and robustness against low-redshift interlopers. A sample of 28 galaxies at z > 7.5 with spectroscopic redshifts shows a low systematic offset and scatter in the difference between photometric and spectroscopic redshifts. We derive the galaxy UV luminosity function at redshifts 8–12, finding a slightly higher normalization than previously seen with the Hubble Space Telescope at redshifts 8–10. We observe a steeper decline in the galaxy space density from z = 8 to 12 than found by most JWST Cycle 1 studies. In particular, we find only eight galaxies at z > 10 and none at z > 12.5, with no z > 10 galaxies brighter than F277W AB = 28 or M UV = −20 in our unmasked, delensed survey area of 53.4 arcmin2. We attribute the lack of bright z > 10 galaxies in CANUCS compared to GLASS and CEERS to intrinsic variance in the galaxy density along different sight lines. The evolution in the CANUCS luminosity function between z = 8 and 12 is comparable to that predicted by simulations that assume a standard star formation efficiency without invoking any special adjustments.