2012ApJ...753..135K

We present a search for CO emission in a sample of 10 type-2 quasar host galaxies with redshifts of z ~ 0.1-0.4. We detect CO(J = 1-0) line emission with ≥ 5σ in the velocity integrated intensity maps of five sources. A sixth source shows a tentative detection at the ∼4.5σ level of its CO(J = 1-0) line emission. The CO emission of all six sources is spatially coincident with the position at optical, infrared, or radio wavelengths. The spectroscopic redshifts derived from the CO(J = 1-0) line are very close to the photometric ones for all five detections except for the tentative detection for which we find a much larger discrepancy. We derive gas masses of ~(2-16)x10⁹ M_☉ for the CO emission in the six detected sources, while we constrain the gas masses to upper limits of M _gas ≤ 8x10⁹ M_☉ for the four non-detections. These values are of the order or slightly lower than those derived for type-1 quasars. The line profiles of the CO(J = 1-0) emission are rather narrow ( ≲ 300 km/s) and single peaked, unveiling no typical signatures for current or recent merger activity, and are comparable to that of type-1 quasars. However, at least one of the observed sources shows a tidal-tail-like emission in the optical that is indicative of an ongoing or past merging event. We also address the problem of detecting spurious ∼5σ emission peaks within the field of view.