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Dust and CO lines in high redshift quasars
S. Guilloteau 1,
A. Omont 2,
P. Cox 3,
R.G. McMahon 4 and
P. Petitjean 2
Received 18 March 1999 / Accepted 16 June 1999
We report the results of a systematic search for redshifted rotational lines of CO and dust emission towards a sample of 9 high redshift radio quiet quasars using the IRAM Plateau de Bure interferometer. Dust emission at mm has been found in 5 out of the 9 objects. These results confirm the corresponding previous detections with the MPIfR bolometer at the 30-m. No 3 mm continuum was detected in any source. The flux densities measured at 1.35 mm with the interferometer are systematically smaller by from the broad-band bolometer fluxes, consistent with an average spectral index of within the calibration uncertainty.
In parallel, searches for CO in significant redshift ranges were performed for 8 of the above sources. 6 sources were not detected. Assuming a line width of km s-1, we obtain typical upper limits of Jy km s-1 at the level in the frequency (redshift) range searched. We report a tentative () detection of the J=3-2 line of CO in Q 1230+1627B, and a unambigous detection of the J=5-4 CO line in the gravitationally lensed radio quiet quasar BRI 0952-0115 at a redshift of . After BR 1202-0725 at (Otha et al. 1996, Omont et al. 1996a), and BRI 1335-0417 at (Guilloteau et al. 1997), this is the third detection of CO at . The velocity-integrated CO(5-4) line flux is , with a linewidth of . The 1.35 mm (250 rest wavelength) dust continuum flux density is 2.230.51 mJy, in agreement with previous measurements at 1.25 mm at the 30-m IRAM telescope. The ratio of the CO to 1.35 mm continuum flux is comparable to that of BRI 1335-0417 and 2-3 times larger than for BR 1202-0725. The angular resolution of the observation is not high enough to give evidence of any extension of the 1.35 mm continuum and 3 mm CO emission.
Key words: galaxies: formation galaxies: quasars: emission lines galaxies: quasars: individual: BRI 0952-0115 galaxies: quasars: individual: Q 1230+1627B cosmology: observations cosmology: early Universe
Send offprint requests to: S. Guilloteau
Online publication: September 2, 1999