A JWST /NIRCam study of key contributors to reionization: the star-forming and ionizing properties of UV-faint z ∼ 7−8 galaxies

ABSTRACT Spitzer/Infrared Array Camera (IRAC) imaging has revealed that the brightest z ∼ 7−8 galaxies often exhibit young ages and strong nebular line emission, hinting at high ionizing efficiency among early galaxies. However, IRAC’s limited sensitivity has long hindered efforts to study the fainter, more numerous population often thought largely responsible for reionization. Here, we use Cosmic Evolution Early Release Science (CEERS) JWST/NIRCam data to characterize 116 ultraviolet (UV)-faint (median MUV = −19.5) z ∼ 6.5−8 galaxies. The spectral energy distributions are typically dominated by young (∼10–50 Myr), low-mass (M* ∼ 108 M⊙) stellar populations, and we find no need for extremely high stellar…

• NS
  National Science Foundation

  Awards: DGE-2137419, 2137419, 2109066, AST-2109066
• UO
  University of Arizona

  Award: NAS5-02015