Submillimeter Galaxies at z~2: Evidence for Major Mergers & Constraints on Lifetimes, IMF and CO-H2 Conversion Factor

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We report sub-arcsecond resolution IRAM PdBI millimeter CO interferometry of four z~2 submillimeter galaxies (SMGs), and sensitive CO (3-2) flux limits toward three z~2 UV-/optically selected star forming galaxies.

• The new data reveal for the first time spatially resolved CO gas kinematics in the observed SMGs.
• Two of the SMGs show double or multiple morphologies, with complex, disturbed gas motions.
• The other two SMGs exhibit CO velocity gradients of ~500 km/s across 0.2 arcsec (1.6 kpc) diameter regions, suggesting that the star forming gas is in compact, rotating disks.