2005ApJ...621L...1K

Using the Australia Telescope Compact Array, we have detected CO (1-0) and CO (5-4) from TN J0924-2201 at z=5.2, the most distant radio galaxy known to date. This is the second highest redshift detection of CO published so far. The CO (1-0) line emission is 250-400 km/s wide with a peak flux density of 520±115 µJy/beam, while the CO (5-4) line emission is 200-300 km/s wide with a peak flux density of 7.8±2.7 mJy/beam. Both transitions are spatially unresolved, but there is marginal evidence for spatial offsets between the CO and the host galaxy; the CO (1-0) is located 28±11 kpc (4".5±1".7) north of the radio galaxy, while the CO (5-4) is located 18±8 kpc (2".8±1".2) south of the radio galaxy. Higher spatial resolution observations are required to determine the reality of these offsets. Our result is the second detection of CO in a high-redshift galaxy without preselection based on a massive dust content.