Quantifying the magnetic field in the Milky Way: new advances in radiative transfer modeling

Stefan Reissl

Poster -- Galactic scale ISM and star formation

I will present selected results from my code POLARIS, which covers multiple facets of the radiative transfer (RT) problem such as simulating line emission as well as dust and synchrotron polarization on galactic scales. Driven by observational equipment capabilities, e.g. Planck and in the near future ALMA and the LCT, in this talk I focus on specific astrophysical applications that currently beg re-evaluation: (1) the physics of grain alignment (2) the observational signatures of magnetic fields through dust and synchrotron polarization in the Milky-Way. I will show that radiation pressure as well as velocity streams acting on grains may render dust polarization useless as a tracer of magnetic field directions. Furthermore, in the POLARIS code I implement the best of our current knowledge synchrotron RT algorithms. Based on this, I derive Milky-Way-like all-sky maps by means of post-processing MHD simulations and investigate the B-field imprint on the observable polarization signal. These results permit us to constrain the parameter space for future observational missions with high accuracy. In combination with observations, this all-encompassing post-processing method allows to shed new light on the classic problems of the galactic magnetic field and the role of B-fields in star formation.

Background image: Robert Hurt, IPAC