Conceptual

JADES Measurement of the Galaxy UV Luminosity Function at Redshift 9 and Above

An observational determination of the rest-frame UV luminosity function of galaxies at redshift z about 9 and higher, using JWST Advanced Deep Extragalactic Survey (JADES) imaging. From several hundred candidates reaching M_UV about -17, the study measures the luminosity function in redshift bins (z ~ 8.5-12 and z ~ 12-16), finds none at z ~ 16-22.5, and fits parametric forms. It reports both an excess of bright galaxies in tension with theoretical models (especially at z above 12) and unexpectedly high faint-end number densities with steep faint-end slopes near -2.3 to -2.5, implying reionization may be appreciably underway by z = 10.