The Redshift and Nature of AzTEC/COSMOS 1: A Starburst Galaxy at z = 4.6

Smolčić, Vernesa and Capak, P. and Blain, A. W. and Salvato, M. and Morić, I. and Riechers, D. A. and Sheth, K. and Murphy, E. and Masters, D. and Scoville, N. Z. (2011) The Redshift and Nature of AzTEC/COSMOS 1: A Starburst Galaxy at z = 4.6. Astrophysical Journal Letters, 731 (2). Art. No. 27. ISSN 2041-8205

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Based on broadband/narrowband photometry and Keck DEIMOS spectroscopy, we report a redshift of z = 4.64^(+0.06)_(–0.08) for AzTEC/COSMOS 1, the brightest submillimeter galaxy (SMG) in the AzTEC/COSMOS field. In addition to the COSMOS-survey X-ray to radio data, we report observations of the source with Herschel/PACS (100, 160 μm), CSO/SHARC II (350 μm), and CARMA and PdBI (3 mm). We do not detect CO(5 → 4) line emission in the covered redshift ranges, 4.56-4.76 (PdBI/CARMA) and 4.94-5.02 (CARMA). If the line is within this bandwidth, this sets 3σ upper limits on the gas mass to ≲8 × 10^9 M_☉ and ≲5 × 10^(10) M_☉, respectively (assuming similar conditions as observed in z ~ 2 SMGs). This could be explained by a low CO-excitation in the source. Our analysis of the UV-IR spectral energy distribution of AzTEC 1 shows that it is an extremely young (≲50 Myr), massive (M * ~ 10^(11) M_☉), but compact (≲2 kpc) galaxy, forming stars at a rate of ~1300 M_☉ yr^(–1). Our results imply that AzTEC 1 is forming stars in a "gravitationally bound" regime in which gravity prohibits the formation of a superwind, leading to matter accumulation within the galaxy and further generations of star formation.

Item Type: Article
Keywords: galaxies: distances and redshifts; galaxies: high-redshift; galaxies: starburst
Date: 2011
Subjects: NATURAL SCIENCES > Physics > Astronomy and Astrophysics
Additional Information: © 2011 American Astronomical Society. Received 2010 December 13; accepted 2011 February 15; published 2011 March 25.
Divisions: Faculty of Science > Department of Physics
Publisher: IOP Publishing
Depositing User: Vernesa Smolčić
Date Deposited: 21 Apr 2015 16:07
Last Modified: 21 Apr 2015 16:07

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