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Session 20 - QSOs.
Oral session, Monday, January 13
Frontenac Ballroom,
The Cloverleaf Quasar at z=2.5 has now been detected in four transitions of CO, one of CI, and one of HCN. We present the results of escape probability modelling of the CO line ratios, showing that the emitting gas is warm, dense, and only borderline optically thick. Because of the high emissivity per unit mass, the total estimated molecular hydrogen mass is much lower than would be obtained using the standard Galactic CO luminosity to H_2 mass conversion factor. We present a new map of the CO(7-6) emission with 0.5'' resolution, which gives an upper limit to the observed source size of < 0.3'', and use this size together with the CO linewidth to derive a dynamical mass. This mass is comfortably above the mass of H_2 derived from the CO line models.
