  We provide a model for the prediction of the electronic and magnetic
configurations of ferromagnetic Fe after an ultrafast decrease or increase of
magnetization. The model is based on the well-grounded assumption that, after
the ultrafast magnetization change, the system achieves a partial thermal
equilibrium. With statistical arguments it is possible to show that the
magnetic configurations are qualitatively different in the case of reduced or
increased magnetization. The predicted magnetic configurations are then used to
compute the dielectric response at the 3p (M) absorption edge, which can be
related to the changes observed in the experimental T-MOKE data. The good
qualitative agreement between theory and experiment offers a substantial
support to the existence of an ultrafast increase of magnetisation, which has
been fiercely debated in the last years.
