Solving the radiative transfer equation in geometrical scale

The presence of magnetic fields in the Sun lead to a plethora of magneto-dynamic phenomena that have triggered (and yet does) the interest of many solar physicist. The study of these physical phenomena relies on the accurate inference of the physical properties from the recorded spectra.

From top to bottom: Continuum intensity map close to the FeI spectral line at 6173.344Å, linear polarization map in between +/-0.5Å around the central wavelength, and the circular polarization map for the same spectral range. Two examples of Stokes Q and V profiles are presented for the highlighted positions.

In this project, we aim to develop a numerical code that solves self-consistently the radiative transfer equation together with the magneto-hydrostatic equation for an area of the solar surface. To that end, it is convenient to implement the radiative transfer equation solver in a geometrical scale as this point simplifies the calculation of the spatial derivatives required to solve the above-mentioned equation. A first step is to solve the radiative transfer equation provided a stratification in height of a set of physical parameters. In the image, we demonstrate the (parallel) capabilities doing so, showing the synthetic polarization maps for the FeI 6173Å spectral line for a snapshot of a sunspot simulation (Rempel, M. 2012, ApJ, 750, 62). The synthesis took 125.13 CPU hours which, divided in 40 processors, was done in 3.12 hours.