Polarized Spectral Line Formation in Turbulent Magnetic Fields:The Zeeman and Hanle Effects

Abstract

We present a short summary of work carried out on the effects of random magnetic fields with finite correlation length on spectral line polarization. The magnetic field is modeled by a step-wise Markovian random process defined by a probability distribution and a correlation length. Micro- and macro-turbulent limits are recovered when this length goes to zero and infinity, respectively. For the Zeeman effect, explicit expressions have been obtained for the mean emergent Stokes parameters and for their r.m.s. fluctuations. Examples illustrate the dependence of the mean Zeeman propagation matrix on the magnetic field distribution, and the dependence of mean Stokes parameters and their r.m.s. fluctuations on the correlation length of the magnetic field. For the Hanle effect, explicit expressions have also been obtained for the mean Stokes parameters. We outline the approach and give an explicit expression for the mean value of Stokes Q