| Presenter: | Hélène Frisch |
| Affiliation: | Observatoire Côte d'Azur, laboratoire Cassiopée, CNRS |
| Title: | The Hanle effect. Decomposition of the Stokes parameters in irreducible components |
| Authors: | H. Frisch |
| Form: | talk |
| Abstract: | It was shown in Faurobert-Scholl (1991) that the Stokes parameters describing linear polarization for the weak-field case can be described by a set of six azimuthally cylindrical functions. This decomposition is possible in a one dimensional medium if scattering of photons can be described by a redistribution matrix in which redistribution in frequency is decoupled from angle redistribution and polarization. The expansion in Faurobert-Scholl is constructed with a Fourier azimuthal expansion of the Hanle redistribution matrix and polarized radiation field. It will be shown that the azimuthal Fourier expansion is actually a multipolar expansion in terms of the irreducible spherical tensors for polarimetry $T^K_Q$ and that the Stokes parameters $I$, $Q$, $U$, $V$ can be expressed in terms of nine cylindrically symmetrical irreducible tensors. The proof will be outlined. It employs a decomposition of the redistribution matrix elements ($i$,$j$) ($i$,$j$ = 0 to 3) in terms of the spherical tensors $T^K_Q(i,\Omega)$ and $T^K_Q(j,\Omega')$, with $\Omega'$ and $\Omega$ the directions of the incoming and scattered beams. Several examples of redistribution matrices which permit the Stokes parameters expansion will be given. |
| Session: | 2. Polarization physics in magnetized media |
| Presentation date: | Monday 17th September |
| Presentation time: | 15:00:00 |