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Paper: ULIRGs at z = 1.5 as Scaled up Spiral Disks
Volume: 396, Formation and Evolution of Galaxy Disks
Page: 405
Authors: Daddi, E.; Dannerbauer, D.; Elbaz, D.; Dickinson, M.; Morrison, G.; Stern, D.; Ravindranath, S.
Abstract: We present the first detection of molecular gas cooling CO emission lines from ordinary massive galaxies at z = 1.5. Two sources were observed with the IRAM Plateau de Bure Interferometer, selected to lie in the mass-star formation rate correlation at their redshift, thus being representative of massive high-z galaxies. With an infrared luminosity of LFIR ∼ 1012 L, these disk-like galaxies are borderline ULIRGs but with star formation efficiency similar to that of local spirals, and an order of magnitude lower than that in submm galaxies. This suggests a CO to total gas conversion factor similar to local spirals, gas consumption timescales approaching 1 Gyr or longer and molecular gas masses reaching ∼ 1011 M, comparable to or larger than the estimated stellar masses. These results support a major role of in situ gas consumption over cosmological timescales and with relatively low star formation efficiency, analogous to that of local spiral disks, for the formation of today’s most massive galaxies.
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