Studying the microlens mass function from statistical analysis of the caustic concentration.

Mediavilla Gradolph, Teresa, Ariza Sánchez, Octavio, Mediavilla Gradolph, Evencio

The statistical distribution of caustic crossings by the images of a lensed quasar depends on the properties of the distribution of microlenses in the lens galaxy. We use a procedure based in inverse polygon mapping (Mediavilla et al. 2006) to easily identify the critical and caustic curves generated by a distribution of stars in the lens galaxy. We analyze the statistical distributions of the number of caustic crossings by a pixel size source for several projected mass density and different mass distributions. We compare the results of simulations with theoretical binomial distributions. Finally we apply this method to the study of stellar mass distribution in QSO 2237+0305.