Detection of 1.6 × 10 10 M ⊙ of Molecular Gas in the Host Galaxy of the z = 5.77 SDSS Quasar J0927+2001

We have detected emission by the CO(5-4) and (6-5) rotational transitions at z = 5.7722 ± 0.0006 from the host galaxy of the SDSS quasar J0927+2001 using the Plateau de Bure Interferometer. The peak line flux density for the CO(5-4) line is 0.72 ± 0.09 mJy, with a line FWHM = 610 ± 110 km s -1 . The implied molecular gas mass is (1.6 ± 0.3) × 10 10 M ☉ . We also detect the 90 GHz continuum at 0.12 ± 0.03 mJy, consistent with a 47 K dust spectrum extrapolated from higher frequencies. J0927+2001 is the second example of a huge molecular gas reservoir within the host galaxy of a quasar within 1 Gyr of the big bang. Observations of J0927+2001 are consistent with a massive starburst coeval with a bright quasar phase in the galaxy, suggesting the rapid formation of both a supermassive black hole through accretion, and the stellar host spheroid, at a time close to the end of cosmic reionization.