Proceedings of Science
We have used the Submillimeter Array (SMA) to image a flux limited sample of seven submillimeter galaxies at 345 GHz with 2" resolution. These galaxies were selected based on fluxes measured using the AzTEC camera on the JCMT at 1.1 mm. All of the sources (two radio-bright and five radio-dim) are unresolved, and we report positions accurate to ~0.2". All of these sources have multiple potential counterparts at other wavelengths within the original AzTEC beam. The astrometric accuracy offered by the SMA - which represents nearly an order of magnitude improvement over single dish imaging - enables us to unambiguously identify counterparts at other wavelengths observed with similarly high angular resolution. Compared to the two radio-bright sources in the sample, and those in previous studies, we find that the five radio-dim sources in the sample: 1) have systematically higher submm-to-radio flux ratios, 2) have lower IRAC 3.6-8.0 µm fluxes, and 3) are not detected at 24 µm. These properties, combined with size constraints at 345 GHz, suggest that the radio-dim submm galaxies in our sample are representative of a population of very dusty starbursts, with physical scales for submm continuum emission similar to local ultraluminous infrared galaxies and an average redshift higher than radio-bright sources. Without the benefit of this positional accuracy, an incorrect counterpart would have been identified for at least two of these sources, resulting in erroneous interpretations of their physical properties.
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© The Authors
Peck, Alison B.; Younger, Joshua D.; Fazio, Giovanni; Huang, Jiasheng; Ashby, Matthew; Gurwell, Mark; Lai, Kamson; Petitpas, Glen; Wilner, David; Yun, Min Su; Wilson, Grant; Scott, Kimberly; Austermann, Jason; Perera, Thushara; Iono, Daisuke; Kohno, Kotaro; Kawabe, Ryohei; Hughes, David; Aretxaga, Itziar; Webb, Tracy; Martinez-Sansigre, Alejo; Schinnerer, Eva; Smolcic, Vernesa; Kim, Sungeun; and Lowenthal, James, "Evidence for a Population of High-Redshift Submillimeter Galaxies from Interferometric Imaging" (2007). Astronomy: Faculty Publications, Smith College, Northampton, MA.