We imaged , with ALMA and ARGOS/LUCI , the molecular gas and dust and stellar continuum in XID2028 , which is an obscured quasi-stellar object ( QSO ) at z=1.593 , where the presence of a massive outflow in the ionised gas component traced by the [ O III ] 5007 emission has been resolved up to 10 kpc .
This target represents a unique test case to study QSO feedback in action at the peak epoch of AGN-galaxy co-evolution .
The QSO was detected in the CO ( 5-4 ) transition and in the 1.3 mm continuum at \sim 30 and \sim 20 \sigma significance , respectively ; both emissions are confined in the central ( < 4 kpc ) radius area .
Our analysis suggests the presence of a fast rotating molecular disc ( v \sim 400 km s ^ { -1 } ) on very compact scales well inside the galaxy extent seen in the rest-frame optical light ( \sim 10 kpc , as inferred from the LUCI data ) .
Adding available measurements in additional two CO transitions , CO ( 2-1 ) and CO ( 3-2 ) , we could derive a total gas mass of \sim 10 ^ { 10 } M _ { \odot } , thanks to a critical assessment of CO excitation and the comparison with the Rayleigh-Jeans continuum estimate .
This translates into a very low gas fraction ( < 5 % ) and depletion timescales of 40-75 Myr , reinforcing the result of atypical gas consumption conditions in XID2028 , possibly because of feedback effects on the host galaxy .
Finally , we also detect the presence of high velocity CO gas at \sim 5 \sigma , which we interpret as a signature of galaxy-scale molecular outflow that is spatially coincident with the ionised gas outflow .
XID2028 therefore represents a unique case in which the measurement of total outflowing mass , of \sim 500 - 800 M _ { \odot } yr ^ { -1 } including the molecular and atomic components in both the ionised and neutral phases , was attempted for a high- z QSO .