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Title: SUBMILLIMETER ARRAY IDENTIFICATION OF THE MILLIMETER-SELECTED GALAXY SSA22-AzTEC1: A PROTOQUASAR IN A PROTOCLUSTER?

We present results from Submillimeter Array (SMA) 860 {mu}m subarcsecond astrometry and multiwavelength observations of the brightest millimeter (S{sub 1.1mm} = 8.4 mJy) source, SSA22-AzTEC1, found near the core of the SSA22 protocluster that is traced by Ly{alpha}-emitting galaxies at z = 3.09. We identify a 860 {mu}m counterpart with a flux density of S{sub 860{sub {mu}m}} = 12.2 {+-} 2.3 mJy and absolute positional accuracy that is better than 0.''3. At the SMA position, we find radio-to-mid-infrared counterparts, whilst no object is found in Subaru optical and near-infrared deep images at wavelengths {<=}1 {mu}m (J > 25.4 in AB, 2{sigma}). The photometric redshift estimate, using flux densities at {>=}24 {mu}m, indicates z{sub phot} = 3.19{sup +0.26}{sub -0.35}, consistent with the protocluster redshift. We then model the near-to-mid-infrared spectral energy distribution (SED) of SSA22-AzTEC1, and find that the SED modeling requires a large extinction (A{sub V} {approx} 3.4 mag) of starlight from a stellar component with M{sub star} {approx} 10{sup 10.9} M{sub sun}, assuming z = 3.1. Additionally, we find a significant X-ray counterpart with a very hard spectrum ({Gamma}{sub eff} = -0.34{sup +0.57}{sub -0.61}), strongly suggesting that SSA22-AzTEC1 harbors a luminous active galactic nuclei (AGNs; L{sub X} {approx} 3more » x 10{sup 44} erg s{sup -1}) behind a large hydrogen column (N{sub H} {approx} 10{sup 24} cm{sup -2}). The AGN, however, is responsible for only {approx}10% of the bolometric luminosity of the host galaxy, and therefore the star formation activity likely dominates the submillimeter emission. It is possible that SSA22-AzTEC1 is the first example of a protoquasar growing at the bottom of the gravitational potential underlying the SSA22 protocluster.« less
Authors:
; ; ;  [1] ; ;  [2] ; ; ;  [3] ; ; ;  [4] ; ; ;  [5] ; ; ;  [6] ;  [7] ;  [8]
  1. Nobeyama Radio Observatory, National Astronomical Observatory of Japan, Nobeyama, Minamimaki, Minamisaku, Nagano 384-1305 (Japan)
  2. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  3. Astronomical Institute, Tohoku University, Aramaki, Aoba, Sendai, Miyagi 980-8578 (Japan)
  4. Institute of Astronomy, University of Tokyo, Osawa, Mitaka, Tokyo 181-0015 (Japan)
  5. Department of Physics, Durham University, Durham DH1 3LE (United Kingdom)
  6. National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588 (Japan)
  7. Instituto Nacional de Astrofisica, Optica y Electronica, Aptdo. Postal 51 y 216, 72000 Puebla (Mexico)
  8. Department of Astronomy, University of Massachusetts, 710 North Pleasant Street, Amherst, MA 01003 (United States)
Publication Date:
OSTI Identifier:
21474495
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 724; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/724/2/1270
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BOLOMETERS; ENERGY SPECTRA; FLUX DENSITY; GALAXY NUCLEI; HYDROGEN; LUMINOSITY; QUASARS; RED SHIFT; SIMULATION; STARS; X-RAY GALAXIES COSMIC RADIO SOURCES; COSMIC RAY SOURCES; COSMIC X-RAY SOURCES; ELEMENTS; GALAXIES; MEASURING INSTRUMENTS; NONMETALS; OPTICAL PROPERTIES; PHYSICAL PROPERTIES; SPECTRA