2025/12/12 by Worku, Keduse, Hsiao, Tiger Yu-Yang, Coe, Dan +9
#Astrophysics of Galaxies (astro-ph.GA) #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2512.11985
We present a catalog of 57 high-redshift z>6 galaxy candidates, including 14 spectroscopic confirmations (z = 6.10 -- 9.25), 2 Little Red Dots (z = 4.77, 5.81), and 2 interlopers (z = 3.23, 3.72), based on \JWST NIRCam imaging (7 filters), NIRSpec spectroscopy (PRISM and G395H), and archival \HST imaging (17 filters) of the strong lensing galaxy cluster MACS0647. Our highest redshift confirmation (z = 9.25) is an Extremely Blue Galaxy (presented in~\citealtYanagisawa2024), and here we identify a spectral turnover likely due to damped Lyman-α. We identify an overdensity of galaxies with spectroscopic redshifts z = 6.1, confirming the z ∼ 6 overdensity identified in \HST images. In one of these galaxies, our high-resolution G395H spectroscopy reveals two spatially resolved components with a velocity difference of ∼90 km/s; if these components are gravitationally bound, this would imply a dynamical mass on the order of ∼ 108 M_\odot given their projected separation. We present spectral line fluxes, widths, and derived physical properties, including stellar masses (108 - 109 M\odot) and metallicities (10% - 40% Z\odot) for our spectroscopic sample. We note half of our NIRSpec data was obtained with standard 3-slitlet nods and half was obtained with single slitlets yielding similar results, demonstrating the power to observe more sources on a densely packed NIRSpec MSA.