Detection of molecular gas in a distant submillimetre galaxy at z=4.76 with ATCA

摘要: We have detected the CO(2-1) transition from submillimetre galaxy (SMG) LESSJ033229.4-275619 at z=4.755 using new Compact Array Broadband Backend system on Australian Telescope Array. These data identified a massive gas reservoir available for star formation first time in an SMG z~5. use luminosity and velocity width (FWHM of 160 km/s) CO(2--1) line emission to constrain dynamical mass Mgas~1.6x10^10 Msun Mdyn(<2kpc)~5x10^10 (0.25/sin^2(i)) Msun, respectively, similar that observed SMGs lower redshifts z~2-4, although we note our CO FWHM is factor ~3 narrower than typically seen SMGs. Together with stellar estimate total baryonic Mbary~1x10^11 consistent this young within uncertainties. Dynamical limits high-redshift galaxies are useful tests models: known z~4-5 as examples systems, find their space density predicted by current models. In addition, these observations helped confirm possess masses consumption timescales necessary be progenitors luminous old red z~3. Our results provide preview science ALMA will enable evolution earliest Universe.