Luminous Infrared Galaxies with the Submillimeter Array. V. Molecular Gas in Intermediate to Late-stage Mergers

We present new high-resolution ALMA (13CO J = 1−0 and J = 2−1) and CARMA (12CO and 13CO J = 1−0) observations of two luminous infrared galaxies (LIRGs), Arp 55 and NGC 2623. The new data are complementary to published and archival submillimeter array observations of 12CO J = 2−1 and J = 3−2. We perform a Bayesian likelihood non-local thermodynamic equilibrium analysis to constrain the molecular gas physical conditions such as temperature, …