High-redshift Galaxy Candidates at z  = 6+ as Revealed by JWST Observations of MACS0647

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 (seven 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, and here we identify a spectral turnover likely due to damped Ly 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 −1 ; if these components are gravitationally bound, this would imply a dynamical mass on the order of ∼10 8 M ⊙ given their projected separation. We present spectral line fluxes, widths, and derived physical properties, including stellar masses (10 8 –10 9 M ⊙ ) and metallicities (10%–40% Z ⊙ ) for our spectroscopic sample. We note half of our NIRSpec data was obtained with standard three-slitlet nods and half was obtained with single slitlets yielding similar results, demonstrating the power to observe more sources on a densely packed NIRSpec microshutter assembly.