Degenerate properties of a singular model for polarization during microlensing by non-compact objects

Abstract

Recently Belokurov and Sazhin considered polarization curves during microlensing for non-compact objects. The con-cluded that the polarization curves for compact and non-compact objects demonstrated very distinguishable shapes, but light curves had similar shapes for compact and non-compact objects in those cases. We analyse their samples and show that the polarization curves coincided for compact and non-compact objects because the radii of non-compact objects are much smaller than the Einstein-Chwolson radius. If the radii of non-compact objects are much greater than the Einstein-Chwolson radius, then the differences between the polarization curves for compact and non-compact objects are connected with the singularity (degeneracy) of the isothermal sphere model, since the differences disappear in the framework of the non-singular isothermal sphere model.