Characterizing Dark Matter Concentrations Through Magnitude Distortions due to Gravitational Lensing

In addition to observing astronomical objects through the electromagnetic radiation they give off, astronomers also study the universe by analyzing gravitational effects on mater. More specifically, one can work back from these observed effects to determine the mass distribution in the universe (both inside and outside galaxies). In this project, we worked on one specific gravitational effect: weak gravitational lensing–that is, the bending of light due to medium-sized clusters of galaxies. In particular, we attempted to measure the mass of unseen matter (also called dark matter) that should be present to produce the observed lensing effects. We analyzed data from the Dark Energy galaxy Survey (DES) simulations, found out where weak lensing occurs, and attempted to fit our model of mass distribution to the data in the simulations. While this problem has been attempted before (with varying degrees of success), the current techniques usually rely on the shape distortion of galaxies caused by weak lensing. In this project, we focused on the magnitude distortions, which should provide a roughly independent measure of lens mass. However, the intrinsic systematic uncertainty associated with this method is larger than in methods using shape distortion calculations, due to the higher amount of noise in the galaxy magnitude distribution.