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

摘要: We report sub-arcsecond resolution IRAM PdBI millimeter CO interferometry of four z~2 submillimeter galaxies (SMGs), and sensitive (3-2) flux limits toward three UV-/optically selected star forming galaxies. The new data reveal for the first time spatially resolved gas kinematics in observed SMGs. Two SMGs show double or multiple morphologies, with complex, disturbed motions. other two exhibit velocity gradients ~500 km/s across 0.2 arcsec (1.6 kpc) diameter regions, suggesting that is compact, rotating disks. Our provide compelling evidence these represent extreme, short-lived 'maximum' events highly dissipative mergers rich resulting high mass surface volume densities are similar to those compact quiescent same redshift range, much higher than local spheroids. From ratio comoving ranges, from comparison exhaustion scales stellar ages, we estimate SMG phase duration about 100 Myrs. analysis optically/UV supports a 'universal' Chabrier IMF as being valid over history find 12CO luminosity total conversion factors at z~2-3 probably assumed z~0. implied fractions our sample range 20 50%.