Robust Method for Determination of Magnetic Field Strength in the Solar Photosphere

The classical method for determining the magnetic field strength from the distance between the peaks of blue and red wings of the Stokes V profile of a magnetically sensitive spectral line is modified. To reduce the influence of noise and to more accurately measure the distance between these peaks, the observed Stokes V profile was approximated by a modified wavelet-function. The parameters of the best fitted approximation function were determined by multidimensional optimization. Following such an approach, the magnetic field strength can be found analytically using such an approximation. We investigate the modified method by means of calculations of the Fe I 1564.8 nm Stokes V and I profiles in a three-dimensional snapshot model atmosphere. Magneto-convection snapshot model with small-scale dynamo action performed by Rempel was used. It was found that the method proposed is less sensitive to noise and the shape of the observed V-signal of the line. This makes it possible to conclude that the approach of determining of the magnetic field strength from the observed splitting of the Fe I 1564.8 nm Stokes V profile is more reliable in comparison with the classical one.