Measuring the Arciness in Arclets

Drexel University, Philadelphia PA

Investigators

Abstract

AST-0205080 Goldberg, David M. One of the outstanding questions in extra-galactic astronomy and cosmology pertains to the search for the missing matter in the universe. Dark matter lies hidden in the largest galaxies and clusters of galaxies, and until the advent of gravitational lensing, there was no way to probe the outer reaches of these objects. Weak lensing analysis has proven a boon to modern astrophysics in that it allows for an accurate measurement of cluster masses without recourse to assumptions about the dynamical state of the system, its composition, or its 3-dimensional geometry. Lensing introduces an elliptical distortion to galaxies behind clusters. The mean ellipticity determined from many background galaxies may then be used to reconstruct the cluster's gravitational potential, and thus its mass distribution. This analysis has already been successfully applied to a number of galaxies, clusters, and to large-scale structure generally. In previous work, the awardee has expanded existing lensing analysis to second-order, thus describing a transition regime in which lensing is too weak to produce dramatic arcs, but for which an arc-like signal can still be detected. The present project will expand upon this previous work. These techniques, if successfully demonstrated, can be applied to a number of existing and publicly available datasets. The award is for seed funding for a proof of concept of advanced lensing analysis. ***