CO (2-1) line emission in redshift 6 quasar host galaxies

Ran Wang, Jeff Wagg, Chris L. Carilli, Fabian Walter, Dominick A. Riechers, Chris Willott, Frank Bertoldi, Alain Omont, Alexandre Beelen, Pierre Cox, Michael A. Strauss, Jacqueline Bergeron, Thierry Forveille, Karl M. Menten, Xiaohui Fan

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We report new observations of CO (2-1) line emission toward five z 6 quasars using the Ka-band receiver system on the Expanded Very Large Array (EVLA). Strong detections were obtained in two of them, SDSSJ092721.82+200123.7 and CFHQS J142952.17+544717.6, and a marginal detection was obtained in another source, SDSS J084035.09+562419.9. Upper limits of the CO (2-1) line emission have been obtained for the other two objects. The CO (2-1) line detection in J0927+2001 together with previous measurements of the CO (6-5) and (5-4) lines reveal important constraints on the CO excitation in the central 10kpc region of the quasar host galaxy. The CO (2-1) line emission from J1429+5447 is resolved into two distinct peaks separated by 12 (6.9kpc), indicating a possible gas-rich, major merging system, and the optical quasar position is consistent with the west peak. This result is in good agreement with the picture in which intense host galaxy star formation is coeval with rapid supermassive black hole (SMBH) accretion in the most distant universe. The two EVLA detections are ideal targets for further high-resolution imaging (e.g., with ALMA or EVLA observations) to study the gas distribution, dynamics, and SMBH-bulge-mass relation in these earliest quasar host galaxy systems.

Original languageEnglish (US)
Article numberL34
JournalAstrophysical Journal Letters
Issue number1
StatePublished - Sep 20 2011

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • galaxies: active
  • galaxies: evolution
  • galaxies: high-redshift
  • molecular data
  • radio lines: galaxies


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