A Long Time Ago in a Galaxy Far, Far Away: A Candidate z ? 12 Galaxy in Early JWST CEERS Imaging

Abstract We report the discovery of a candidate galaxy with photo- z ? 12 in first epoch James Webb Space Telescope (JWST) Cosmic Evolution Early Release Science Survey. Following conservative selection criteria, we identify source robust phot = 11.8 ? 0.2 + 0.3 (1 ? uncertainty) m F200W 27.3 and ?7 detections five filters. The is not detected at ? < 1.4 ? deep imaging from both Hubble (HST) JWST has faint ?3 F150W HST F160W, which signal Ly ? break near red edge filters, implying 12. This object (Maisie’s Galaxy) exhibits F115W ? > 1.9 mag (2 lower limit) blue continuum slope, resulting 99.6% probability distribution function favoring 11. All data-quality images show no artifacts candidate’s position, independent analyses consistently find strong preference for Its colors are inconsistent Galactic stars, it resolved ( r h 340 ± 14 pc). Maisie’s Galaxy log M * / ? 8.5 highly star-forming (log sSFR ?8.2 yr ?1 ), rest-UV color ? ?2.5) indicating little dust, though extremely low metallicity. While presence this tension most predictions, agrees empirical extrapolations assuming UV luminosity functions that smoothly decline increasing redshift. Should follow-up spectroscopy validate redshift, our universe was already aglow galaxies less than 400 Myr after Big Bang.