|Gauging the Turbulent Mach Numbers in Optically Thick Clouds
|459, 6th International Conference of Numerical Modeling of Space Plasma Flows (ASTRONUM 2011)
|Burkhart, B.; Lazarian, A.; Ossenkopf, V.; Stutzki, J.
|Magnetohydrodynamic (MHD) Turbulence is a critical component of the current paradigms of star formation, particle transport, magnetic reconnection and evolution of the ISM.
Progress on this difficult subject is made via theoretical predictions, numerical simulations and observational studies.
For star forming molecular clouds in particular,
turbulence plays a role in supporting clouds from gravitational collapse and dense filamentary structures created by shocks via supersonic turbulence could act as a catalyst for stellar birth.
However, diagnosing turbulence in these dense molecular regions is not straightforward, with additional complications including
varying optical depth effects and thermal excitation. We study the probability distribution functions (PDFs) of simulations of MHD turbulence with radiative transfer effects included (specifically looking at the
13CO 2-1 transition) in order
to gauge whether the sonic Mach number can be determined in optically thick turbulent environments. From the simulations, we create synthetic integrated
intensity maps with different sonic Mach numbers and vary optical depth and thermal excitation by changing the average density(ρ) and molecular abundance (X/H2).
We show that PDF descriptors such as the moments and the Tsallis distribution are sensitive to the changes in optical depth as well as the
sonic Mach number in 13CO 2-1 integrated intensity maps.
This opens up avenues for studying the relationship between the compressibility of GMC clouds and star formation using simple statistical methods.