Field distribution of magnetograms from simulations of active region formation

Abstract

Context. The evolution of the photospheric magnetic field distributions (probability densities) has previously been derived for a set of active regions. Photospheric field distributions are a consequence of physical processes that are difficult to determine from observations alone. Aims. We analyse simulated magnetograms from numerical simulations, which model the emergence and decay of active regions. These simulations have different experimental set-ups and include different physical processes, allowing us to investigate the relative importance of convection, magnetic buoyancy, magnetic twist, and braiding for flux emergence. Methods. We specifically studied the photospheric field distributions (probability densities found with a kernel density estimation analysis) and compared the results with those found from observations. Results. Simulations including convection most accurately reproduce the observed evolution of the photospheric field distributions during active region evolution. Conclusions. This indicates that convection may play an important role during the decay phase and also during the formation of active regions, particularly for low flux density values.