High-sensitivity Array Observations of the z = 1.87 Submillimeter Galaxy GOODS 850-3

Type Journal Article
Names Emmanuel Momjian, Wei-Hao Wang, Kirsten K. Knudsen, Christopher L. Carilli, Lennox L. Cowie, Amy J. Barger
Publication The Astronomical Journal
Volume 139
Issue 4
Pages 1622-1627
Date April 1, 2010
URL http://adsabs.harvard.edu/abs/2010AJ....139.1622M
Library Catalog NASA ADS
Abstract We present sensitive phase-referenced Very Long Baseline Interferometry (VLBI) results on the radio continuum emission from the z = 1.87 luminous submillimeter galaxy (SMG) GOODS 850-3. The observations were carried out at 1.4 GHz using the High-Sensitivity Array (HSA). Our sensitive tapered VLBI image of GOODS 850-3 at 0farcs47 × 0farcs34 (3.9 × 2.9 kpc) resolution shows a marginally resolved continuum structure with a peak flux density of 148 ± 38 μJy beam-1, and a total flux density of 168 ± 73 μJy, consistent with previous Very Large Array and MERLIN measurements. The deconvolved size of the source is 0farcs27(±0farcs12) × <0farcs23, or 2.3(±1.0) × <1.9 kpc, and the derived intrinsic brightness temperature is >(5 ± 2) × 103 K. The radio continuum position of this galaxy coincides with a bright and extended near-infrared source that nearly disappears in the deep Hubble Space Telescope optical image, indicating a dusty source of nearly 9 kpc in diameter. No continuum emission is detected at the full VLBI resolution (13.2 × 7.2 mas, 111 × 61 pc), with a 4σ point source upper limit of 26 μJy beam-1, or an upper limit to the intrinsic brightness temperature of 4.7 × 105 K. The extent of the observed continuum source at 1.4 GHz and the derived brightness temperature limits are consistent with the radio emission (and thus presumably the far-infrared emission) being powered by a major starburst in GOODS 850-3, with a star formation rate of ~2500 M sun yr-1. Moreover, the absence of any continuum emission at the full resolution of the VLBI observations indicates the lack of a compact radio-loud active galactic nucleus in this z = 1.87 SMG. Based in part on observations obtained at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii, and the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.
Tags galaxies: active, galaxies: high-redshift, galaxies: individual: GOODS 850-3, radio continuum: galaxies, techniques: interferometric
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