James Webb Space Telescope Feed Post


Literature
Date: 8/8/2023

UNCOVER: Illuminating the Early Universe -- JWST/NIRSpec Confirmation of z > 12 Galaxies Published: 8/7/2023 8:52:11 PM Updated: 8/7/2023 8:52:11 PM

Paper abstract: Observations of high-redshift galaxies provide a critical direct test to thetheories of early galaxy formation, yet to date, only four have beenspectroscopically confirmed at z>12. Due to strong gravitational lensing overa wide area, the galaxy cluster field Abell~2744 is ideal for searching for theearliest galaxies. Here we present JWST/NIRSpec observations of two galaxies: arobust detection at z = 12.40, and a plausible candidate at z = 13.08. Thegalaxies are discovered in JWST/NIRCam imaging and their distances are inferredwith JWST/NIRSpec spectroscopy, all from the JWST Cycle 1 UNCOVER Treasurysurvey. Detailed stellar population modeling using JWST NIRCam and NIRSpec datacorroborates the primeval characteristics of these galaxies: low mass (~10^8 ~{\rm M_\odot}), young, rapidly-forming, metal-poor, and star-forming.Interestingly, both galaxies are spatially resolved, having lensing-correctedrest-UV effective radii on the order of 300--400 pc. These sizes are notablylarger than other z>10 systems, implying significant scatter in the size-massrelation at early times. Deep into the epoch of reionization, these discoverieselucidate the emergence of the first galaxies.