Cake Talk by Ryan Endsley from University of Texas
Over the past decade, a wealth of imaging data have revealed that the brightest reionization-era galaxies often exhibit young ages and strong nebular line emission, hinting at high ionizing efficiency among early galaxies. However, Spitzer/IRAC’s limited sensitivity has long hindered efforts to study the fainter, more numerous z>6 population often thought largely responsible for reionization. In this talk, we present the first detailed study of the star-forming and ionizing properties of ~1000 UV-faint (-20 < Muv < -16.5) z~6-9 galaxies combining data from the CEERS and JADES Cycle 1 programs. We discuss the light-weighted ages, stellar masses, nebular line emission strengths, and dust attenuation as a function of UV magnitude, remarking on implications for the formation and ionizing efficiency of faint reionization-era galaxies. We conclude by describing potential evidence for bursty star formation histories among this sample and comment on how such star formation histories may help explain the presence of very bright z>10 galaxies that are now being spectroscopically confirmed.