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Abstract Detail

13 January, 2006 - 11:20 AM

CO line SEDs of high-z QSOs and submm Galaxies

A. Weiss (MPIfR Bonn), D. Downes, C. Henkel, & F. Walter

Observations of multiple CO transitions provide a unique tool to constrain the excitiation conditions of the molecular gas in high redshift objects. We present first results of our ongoing multi CO transitions study in six QSOs host galaxies and four submm-galaxies at redshifts between z=1.4 and 4.7 obtained at the IRAM 30m telescope and the IRAM Plateau de Bure interferometer. Observed CO lines typically include transitions between CO(3-2) and CO(8-7) but range up to the CO(11-10) line in the BAL QSO APM0827 (z=3.9). This unique set of rest frame mm/submm transitions provides, for the first time, information on the full CO ladder in ultra luminous infrared galaxies at any redshift. Using Large Velocity Gradient (LVG) models we conclude that, surprisingly, all CO line SEDs (CO flux density vs. rotational quantum number) can be explained by single temperature/density models. We will discuss variations of the CO line SEDs and of the underlying physical conditions within the massive molecular gas reservoirs found in these high-z objects.


Conference Photo by Jim Condon - Click to enlarge