GMC Collisions as Triggers of Star Formation. V. Observational Signatures

Abstract

We present calculations of molecular, atomic, and ionic line emission from simulations of giant molecular cloud (GMC) collisions. We post-process snapshots of the magnetohydrodynamical simulations presented in an earlier paper in this series by Wu et al. of colliding and non-colliding GMCs. Using photodissociation region (PDR) chemistry and radiative transfer, we calculate the level populations and emission properties of the transitions of 12 CO J  = 1–0, [C i ] 3 P 1 → 3 P 0 at 609 μ m, [C ii ] 158 μ m, and [O i ] 3 P 1 → 3 P 0 at 63 μ m. From emission maps of integrated intensity and position–velocity diagrams, we find that fine-structure lines, particularly [C ii ] 158 μ m, can be used as a diagnostic tracer for cloud–cloud collision activity. These results hold even in more evolved systems in which the collision signature in molecular lines has been diminished.