Contributed Talk - Splinter ISM

Thursday, 24 September 2020, 11:15   (virtual room F)

Compressible turbulence: simulations and observational detection

Huirong Yan, Heshou Zhang, Kirit Makwana

The multiphase nature of ISM and diversity of driving mechanisms give rise to spatial variation of turbulence properties. In particular, we find that the proportion of magnetosonic modes increases with increasing compressive forcing from our turbulence simulations with generalized driving. Nevertheless, the employed model of turbulence is often oversimplified being assumed to be only Alfvenic or even hydrodynamic due to a lack of observational evidence. Employing our novel method, the signature from polarization analysis (SPA), we unveiled the dominant plasma modes in interstellar turbulence. The method is based on the statistical properties of the Stokes parameters (I,Q,U) of the synchrotron radiation polarization. We find that Alfven and magnetosonic modes are distinguishable. Its application leads to the first discovery of magnetosonic modes in the Cygnus X region, overlapping to a high degree with Fermi cocoon, consistent with theoretical expectations. Moreover, through comparison with the spectrum at other wavelengths, the plasma modes of turbulence are unveiled in active star formation zones and supernova remnant.