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Title: Karl G. Jansky very large array observations of cold dust and molecular gas in starbursting quasar host galaxies at z ∼ 4.5

We present Karl G. Jansky Very Large Array (VLA) observations of 44 GHz continuum and CO J = 2-1 line emission in BRI 1202–0725 at z = 4.7 (a starburst galaxy and quasar pair) and BRI 1335–0417 at z = 4.4 (also hosting a quasar). With the full 8 GHz bandwidth capabilities of the upgraded VLA, we study the (rest-frame) 250 GHz thermal dust continuum emission for the first time along with the cold molecular gas traced by the low-J CO line emission. The measured CO J = 2-1 line luminosities of BRI 1202–0725 are L{sub CO}{sup ′}=(8.7±0.8)×10{sup 10} K km s{sup –1} pc{sup 2} and L{sub CO}{sup ′}=(6.0 ± 0.5)×10{sup 10} K km s{sup –1} pc{sup 2} for the submillimeter galaxy (SMG) and quasar, respectively, which are equal to previous measurements of the CO J = 5-4 line luminosities implying thermalized line emission, and we estimate a combined cold molecular gas mass of ∼9×10{sup 10} M {sub ☉}. In BRI 1335–0417 we measure L{sub CO}{sup ′}=(7.3±0.6)×10{sup 10} K km s{sup –1} pc{sup 2}. We detect continuum emission in the SMG BRI 1202–0725 North (S {sub 44} {sub GHz} = 51 ± 6 μJy), while the quasar is detected withmore » S {sub 44} {sub GHz} = 24 ± 6 μJy and in BRI 1335–0417 we measure S {sub 44} {sub GHz} = 40 ± 7 μJy. Combining our continuum observations with previous data at (rest-frame) far-infrared and centimeter wavelengths, we fit three-component models in order to estimate the star formation rates. This spectral energy distribution fitting suggests that the dominant contribution to the observed 44 GHz continuum is thermal dust emission, while either thermal free-free or synchrotron emission contributes less than 30%.« less
Authors:
 [1] ; ; ; ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9]
  1. Square Kilometre Array Organisation, Lower Withington, Cheshire (United Kingdom)
  2. Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom)
  3. European Southern Observatory, Casilla 19001, Santiago (Chile)
  4. Joint ALMA Observatory, Santiago (Chile)
  5. Institute of Astronomy, University of Cambridge, Cambridge (United Kingdom)
  6. Cornell University, Ithaca, NY (United States)
  7. Max-Planck Institute for Astronomy, Heidelberg (Germany)
  8. European Southern Observatory, Garching (Germany)
  9. Department of Physics and Center for Astrophysics and Space Sciences, UCSD, La Jolla, CA (United States)
Publication Date:
OSTI Identifier:
22351326
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 783; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON MONOXIDE; COSMOLOGY; DUSTS; EMISSION; ENERGY SPECTRA; EVOLUTION; GALAXIES; GHZ RANGE; LUMINOSITY; MASS; QUASARS; RED SHIFT; STARS; SYNCHROTRONS; UNIVERSE; WAVELENGTHS