Remarkably high mass and high velocity dispersion of molecular gas associated with a regular, absorption-selected type-I quasar
Optical observations of the quasar J0015+1842 at z=2.6 have recently revealed the presence of multi-phase outflowing winds intercepted by the line of sight to the active nucleus. Here, we present 3-mm observations of this system with the NOrthern Extended Millimeter Array (NOEMA). Our data reveals molecular gas, traced via a Gaussian CO(3-2) line, with a remarkably large velocity dispersion (FWHM=1014+/-120 km/s). The integrated line flux indicates a total molecular mass in the range M_H2 ~ (3.4-17)x10^10 Msun, with the spread dominated by the assumed CO-to-H2 conversion factor. Assuming the 3-mm continuum emission is thermal, we derive a dust mass of Mdust ~ 2x10^9 Msun. J0015+1842 is located in the molecular gas-rich region in the IR vs CO line luminosity diagram, in-between the main locus of main-sequence and sub-millimeter galaxies and that of most other AGNs targeted so far for CO measurements. While the large velocity dispersion of the CO line suggests a post merger system, J0015+1842 is observed to be a regular, only very moderately dust-reddened (Av~0.3-0.4) type-I quasar from its UV-optical spectrum, from which we infer a mass of the super-massive black hole be around M_BH~6x10^8 Msun. We suggest that J0015+1842 is observed at a galaxy evolutionary stage where a massive merger has brought significant amounts of gas towards an actively accreting super-massive black hole (quasar) that already cleared the way in the circum-nuclear region towards the observer through powerful winds, while the host still contains a large amount of dust and molecular gas with high velocity dispersion. Observations of a sample of similar systems should help determining better the respective importance of evolution and orientation in the appearance of quasars and their host galaxies and have the potential to investigate early feedback and star-formation processes in galaxies in their quasar phases.