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JADES Imaging of GN-z11: Revealing the Morphology and Environment of a Luminous Galaxy 430 Myr after the Big Bang

Paper abstract: We present JWST NIRCam nine-band near-infrared imaging of the luminous z = 10.6 galaxy GN-z11 from the JWST Advanced Deep Extragalactic Survey of the GOODS-N field. We find a spectral energy distribution (SED) entirely consistent with the expected form of a high-redshift galaxy: a clear blue continuum from 1.5 to 4 µm with a complete dropout in F115W. The core of GN-z11 is extremely compact in JWST imaging. We analyze the image with a two-component model, using a point source and a Sérsic profile that fits to a half-light radius of 200 pc and an index n = 0.9. We find a low-surface-brightness haze about 0."4 to the northeast of the galaxy, which is most likely a foreground object but might be a more extended component of GN-z11. At a spectroscopic redshift of 10.60 (Bunker et al. 2023), the comparison of the NIRCam F410M and F444W images spans the Balmer jump. From population-synthesis modeling, here assuming no light from an active galactic nucleus, we reproduce the SED of GN-z11, finding a stellar mass of ~109M?, a star formation rate of ~20 M? yr-1, and a young stellar age of ~20 Myr. Since massive galaxies at high redshift are likely to be highly clustered, we search for faint neighbors of GN-z11, finding nine galaxies out to ~5 comoving Mpc transverse with photometric redshifts consistent with z = 10.6, and a tenth more tentative dropout only 3" away. This is consistent with GN-z11 being hosted by a massive dark-matter halo (˜8 × 1010M?), though lower halo masses cannot be ruled out.