The Molecular Disk in the Cloverleaf Quasar

We propose a new interpretation for the CO emitting region of the Cloverleaf (H1413+1143), a gravitationally lensed QSO. We fit a two-galaxy lensing model directly to the IRAM CO(7-6) data rather than to the optical HST image and from the fit we infer that the CO(7-6) source is a disk-like structure with a characteristic radius of $785 {\rm pc} (in the currently widely accepted cosmology: cosmological constant $\Omega_{\Lambda}=0.7$, matter content $\Omega_{m}=0.3$, and Hubble constant $H_{0}=65 {\rm km s^{-1} mpc}^{-1}$), a size similar to that of the CO emitting regions present in nearby starburst ultraluminous infrared galaxies. We therefore suggest that the Cloverleaf contains both an extended rotating molecular starburst disk and a central quasar.