Molecular Tracers of Turbulent Shocks in Molecular Clouds Andy Pon University of Victoria, Victoria, Canada
The observed supersonic turbulence in molecular clouds may play a vital role in supporting clouds against collapse, but this turbulence is predicted to decay quickly unless driven by an energy source. While much observational and theoretical effort has been spent on identifying possible energy sources, little has been done to observationally constrain the rate at which turbulent energy is dissipated. We have run models of C-type shocks, based on Kaufman & Neufeld (1996), propagating into gas with densities around 1000 cm^-3 at velocities of a few km / s, appropriate for the ambient conditions inside of a molecular cloud, to determine which species and transitions dominate the cooling and radiative energy release associated with shock cooling of turbulent molecular clouds. Combining these models of shock emission and estimates for the rate of turbulent energy dissipation (Basu & Murali 2001), based upon the conditions in nearby molecular clouds, we produce synthetic CO spectra and predict those line emissions that will be observable with current and upcoming observational facilities such as Herschel, ALMA and CCAT. In particular, we find that the CO J = 6-5 and 7-6 lines are powerful shock tracers. We also present shock models for a density of 10^5 cm^-3 to predict the shock emission expected for a quiescent IRDC.
Collaborators: D. Johnstone, NRC-HIA, Canada M. J. Kaufman, San Jose State University, USA	Key publication