Collaborative Research: A Three-Dimensional Analysis of the Gas and Dark Matter in the CLASH Clusters of Galaxies

Michigan State University, East Lansing MI

Investigators

Abstract

The team will use their state-of-the-art model to analyze submillimeter, optical and X-ray observations of 25 clusters of galaxies. The model will reveal if the clusters are shaped like baseballs, cigars, pancakes or something more complex. Once the cluster shapes are known, the cluster masses will be estimated with unprecedented accuracy. This will give cosmologists a powerful new tool to study why the universe evolves as it does. The team will release their modeling code to the public. Senior team members will train junior members. The team will also develop free on-line teaching materials and interact with high school students in low-income areas. The team will analyze extensive observations of clusters of galaxies to form three-dimensional reconstructions of their dark matter and gaseous matter. Inferences in three dimensions stem from differences in how the X-ray and Sunyaev-Zeldovich signals vary within a cluster. The reconstructions will vastly improve the accuracy of cluster-mass estimates. This, in turn, will improve cluster-based cosmology. The team's specific goals are to measure for each cluster (1) the major-axis orientation to +/-15 degrees and the axial ratio to +/-0.15; (2) the ratio of non-thermal to thermal pressures, achieving +/-0.2 in the outskirts; and (3) the three-dimensional mass profile, achieving +/-0.1 in the concentration parameter. To quantify the robustness of the measurements, the team will also evaluate (1), (2) and (3) for mock observations of simulated clusters.