CO and Dust in PSS 2322+1944 at a redshift of 4.12

¹ Institut d'Astrophysique Spatiale, Université de Paris XI, 91405 Orsay, France
² Institut d'Astrophysique de Paris, CNRS, 98bis boulevard Arago, 75014 Paris, France
³ Astronomy Department, California Institute of Technology, Pasadena, CA 91125, USA
⁴ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
⁵ IRAM, 300 rue de la Piscine, 38406 St-Martin-d'Hères, France
⁶ National Radio Astronomy Observatory, PO Box O, Socorro, NM 87801, USA
⁷ Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE, UK
⁸ Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK
⁹ Infrared Processing and Analysis Center 100-22, Caltech, Pasadena, CA 91125, USA

Corresponding author: P. Cox, pierre.cox@ias.u-psud.fr

Received: 11 January 2002
Accepted: 8 March 2002

Abstract

Using the IRAM interferometer we have detected and CO line emission toward the radio quiet quasar PSS 2322+1944. At a redshift of this is the fourth and strongest detection of CO at . The velocity-integrated CO and line fluxes are and , and the linewidth is . The CO was searched for but not detected with an upper intensity limit of 30 mJy. The 1.35 mm (250  rest wavelength) continuum flux density is  mJy, in agreement with previous bolometer measurements at 1.2 mm with the 30-m IRAM telescope. The 3 mm (580  rest wavelength) continuum is not detected with a 3 σ upper limit of 0.7 mJy. We also report observations of the 450  continuum in PSS 2322+1944 using the SCUBA array at the JCMT. The quasar was detected with a 450  flux density of . At the angular resolution of at 1.3 mm and at 3.2 mm, the interferometer observations do not show evidence of spatial extension in the continuum or CO line emission. Assuming no gravitational magnification, we estimate a molecular gas mass of . The molecular gas is warm () and dense (). The infrared-to-CO luminosity ratio is , comparable to the values found for ultraluminous infrared galaxies. The detection of CO emission in this high redshift QSO provides further evidence that the radio emission and the millimeter to submillimeter continuum emission are predominantly powered by a starburst which is coeval with the AGN activity.