The Host Galaxies of Optical Bright QSOs: Molecular Gas in Z < 0.1 PG-QSOs

Abstract

We present results of a CO(1-0) line survey in a complete sample of 12 low redshift (Z < 0.1), optically bright QSOs (PG QSOs with M_B < -23 mag). Six new CO detections are reported here at levels exceeding I_CO ~2 Jy km/s. Combined with three previously reported detections, we find that 9 of the 12 QSOs have abundant, dense ISMs characteristic of late type galaxies. In all 9 of the detected QSOs, the derived molecular gas masses are M(H2) > 1.0e9 M_solar, with the most massive being 1e10 M_solar ~(PG 0050+124 -- I Zw 1). In the three sources not yet detected in CO, the upper limits on the gas masses are ~ 1e9 M_solar and thus we cannot rule out abundant ISMs even in these objects. Since our sample was chosen entirely on the basis of low redshift and optical luminosity (and not selected for strong infrared emission), we conclude that the majority of luminous, low redshift QSOs have gas-rich host galaxies and therefore can not be normal elliptical galaxies.

13 pages, 2 figures, submitted to ApJ Letters