Search for molecular gas in the quasar SDSS 1044-0125 at z=5.73

We report upper limits on CO J = 2-1 and J = 5-4 emission from the quasar SDSSp J104433.04-012502.2, at z = 5.73, from observations made with the Berkeley-Illinois-Maryland Association array. Previously reported limits on CO J = 6 5 emission were obtained at z = 5. 80, which is now thought to be off by 1%, and the observations likely missed the relevant redshifts for molecular gas. The new 3 sigma upper limits on the line luminosities are L-CO'(2-1) < 5.1 x 10(10) K km s(-1) pc(2) and L-CO'(5-4) < 3.0 x 10(10) K km s(-1) pc(2), assuming 200 km s(-1) line width. The CO J = 5-4 observations place an upper limit on warm, dense molecular gas mass comparable to amounts derived for some other high-redshift quasar systems from detections of this line. The limit on CO J = 2 1 emission suggests that excitation bias does not affect this conclusion. In addition, no companion galaxies rich in molecular gas are found in a similar to1.4 Mpc field surrounding the quasar.