Younger, JDFazio, GGWilner, DJAshby, MLNBlundell, RGurwell, MAHuang, JSIono, DPeck, ABPetitpas, GRScott, KSWilson, GWYun, Min2024-04-262024-04-262008-0110.1086/591931https://hdl.handle.net/20.500.14394/3414<p>This is the pre-published version harvested from ArXiv. The published version is located at <a href="http://iopscience.iop.org/0004-637X/688/1/59/">http://iopscience.iop.org/0004-637X/688/1/59/</a></p>We present high-resolution submillimeter interferometric imaging of two of the brightest high-redshift submillimeter galaxies known: GN 20 and AzTEC1 at 0.8'' and 0.3'' resolution, respectively. Our data—the highest resolution submillimeter imaging of high-redshift sources accomplished to date—were collected in three different array configurations: compact, extended, and very extended. We derive angular sizes of 0.6'' and 1.0'' for GN 20 and 0.3'' and 0.4'' for AzTEC1 from modeling their visibility functions as a Gaussian and an elliptical disk, respectively. Because both sources are B-band dropouts, they likely lie within a relatively narrow redshift window around z ~ 4, which indicates their angular extent corresponds to physical scales of 4-8 and 1.5-3 kpc, respectively, for the starburst region. By way of a series of simple assumptions, we find preliminary evidence that these hyperluminous starbursts—with star formation rates >1000 M yr−1—are radiating at or close to their Eddington limit. Should future high-resolution observations indicate that these two objects are typical of a population of high-redshift Eddington-limited starbursts, this could have important consequences for models of star formation and feedback in extreme environments.cosmology: observationsgalaxies: evolutiongalaxies: formationgalaxies: high-redshiftgalaxies: starburstAstrophysics and Astronomyarticle