2003/04/02 by D. T. Frayer, L. Armus, N. Z. Scoville +5
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1086/375653
published as Astron.J. 126 (2003) 73 · 13 pages including 6 figures, Accepted AJ
arxiv created 2003/04/02 · openalex publication_date 2003/07/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/01
We report the redshift measurement for the submillimeter selected galaxy SMM J04431+0210 (N4) using the Near Infrared Spectrograph on the Keck II Telescope. The data show Hα, [N II] λλ6583, 6548, and [O III] λ5007 lines at a redshift of z = 2.51. The high nuclear [N II]/Hα line ratio is consistent with a LINER or type II active galactic nucleus (AGN). The Hα emission is spatially resolved, suggesting the presence of significant star-forming activity outside the nucleus. From imaging with the Near Infrared Camera on the Keck I Telescope, we find an extremely red near-infrared color of J - K = 3.2 for N4. Follow-up redshifted CO(3→2) observations with the Owens Valley Millimeter Array constrain the mass of molecular gas to be less than 4 × 10 10 M ⊙ , after correcting for lensing. The CO-to-submillimeter flux limit, the spectroscopic line ratios, and the spectral energy distribution for N4 are all within the range of properties found in other high-redshift submillimeter sources and local ultraluminous infrared galaxies. After the correction for lensing, N4 is the weakest intrinsic submillimeter-selected source with a known redshift and represents the first redshift for the under 2 mJy 850 μm sources that are responsible for the bulk of the emission from the submillimeter population as a whole. We argue that N4 contains either an AGN or LINER nucleus surrounded by an extended region of active star formation.