The second detection of CO at redshift larger than 4

Abstract

We report the detection with the IRAM interferometer at 3mm of J=5-4 CO line in the radio quiet quasar BRI1335-0415 at redshift of z=4.41. After BR1202-0725 at z=4.69 (Ohta etal 1996, Omont etal 1996a), this is the second detection of CO at z>3. The integrated line intensity is 2.8+-0.3 Jy km s^{-1} with a linewidth of 420+-60 km s^{-1}. The dust continuum emission has also been mapped at 1.35mm. The 1.35mm flux is found to be 5.6+-1.1mJy. The ratio of the CO to 1.35mm continuum flux is slightly larger than for BR1202-0725. Contrary to the case of BR1202-0725, there is only marginal evidence of extension of the 1.35mm continuum and 3mm CO emission. In the absence of gravitational lensing, for which there is no a priori evidence, and within the uncertainties of the CO to M(H_2) conversion factors, the mass of molecular gas M(H_2) could be 10^{11} solar masses.