PI: Ian Dell'Antonio, Brown University, firstname.lastname@example.org
Address: Physics Department, Box 1843, Brown University, Providence, Rhode Island 02912, USA
CoI: Jacqueline McCleary, Brown University
CoI: Ryan Michney, Brown University
CoI: Paul Huwe, Brown University
Title: Measuring the Evolution of mass substructures in clusters: Substructure at z=0.25
Abstract: We propose to use the superior image quality of pODI on WIYN to perform high signal-to-noise lensing detections of three 0.25 < z < 0.30 clusters from the HeCS sample. These are the only three clusters in the sample that lack high quality (with seeing better than 0.7 arcseconds) imaging, allowing for the study of a complete X-ray selected sample of clusters with multiple independent mass determinations (from weak lensing, X-ray profiles, and infall profile fitting). We will construct 2-dimensional maps of the mass distribution to detect mass substructures containing >20% of the cluster mass. This sample of clusters represents the critical link in the study of the evolution of cluster mass substructure from z=0.8 to the current epoch. Measuring the evolution of substructure is important for understanding the redshift-dependent bias in weak lensing calibrations of the cluster mass function, one of the four key techniques for constraining dark energy. In addition, the distribution of substructure is itself emerging as an independent test of cosmology. These observations will also enable the study of the properties of galaxies as a function of the local mass environment, taking advantage of the large number of cluster galaxy spectra.
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