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

We present calculations of molecular, atomic and ionic line emission from simulations of giant molecular cloud (GMC) collisions. We post-process snapshots of the magneto-hydrodynamical simulations presented in an earlier paper in this series by Wu et al. (2017) of colliding and non-colliding GMCs. Using photodissociation region (PDR) chemistry and radiative transfer we calculate the level populations and emission properties of ${}^{12}$CO $J=1-0$, [CI] $^3{\rm P}_1\rightarrow{^3{\rm P}}_0$at$609,\mu$m,[CII]$158,\mu$mand[OI]$^3{\rm P}_1\rightarrow{^3{\rm P}}_0$transitionat$63,\mu$m. From integrated intensity emission maps and position-velocity diagrams, we find that fine-structure lines, particularly the [CII] $158\mu$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.