A new analysis method for solar surface magnetism

Standard algorithms for tracking small scale magnetic features suffer
from ambiguities due to the intrinsic complexity of the feature
interactions which are driven by photospheric convective motions.

In his Ph.D. work, Andrei Gorobets will work on an alternative concept
for tracking the evolution of photospheric magnetic features, which
sidesteps the uncertainties of conventional direct feature tracking
methods. The new method essentially considers the magnetic flux
evolution pixel by pixel in a time-ordered sequence of magnetograms: the
flux in each pixel above a noise threshold is tracked if it has a given
minimum lifetime. The change of flux over time is then monitored and
analysed for each pixel and its neighbors. The magnetograms are treated
as if they were snapshots of the instant microstate configuration of a
“pixel gas” in a continuous medium, meaning that statistics can be used
to analyse the random "pixel flux" variations.

In the framework of kinetic gas theory it can be shown that the pixel
fluxes obey a geometrical random walk model, from which master equations
and the Fokker-Planck equations for the pixel flux probability density
can be estimated. The applicability of the fluctuation theorem can be
proven using a thermodynamical approach which can then be used to study
irreversibility measures of the pixel flux stochastic dynamics.

A comparative study is planned to test the new method for small-scale
magnetic features of the quiet Sun registered by SDO/HMI, Sunrise/IMaX,
and various MHD simulations.