Séminaires et colloques

Mass estimation of galaxy clusters with weak gravitational lensing

by Dr Calum Murray (LPSC)

Virtual ZOOM (LPSC)

Virtual ZOOM



The formation of galaxies clusters through gravitational collapse depend sensitively on the properties of dark energy and dark matter. Through the study of these objects we hope to reveal the nature of these mysterious energy components of the universe. An important observational tool to this aim is weak gravitational lensing in which the projected matter density of clusters can be reconstructed from the subtle distortion of galaxy shapes by a foreground cluster. With the future Euclid satellite we will observe on the order of 100,000 galaxy clusters across a range of redshifts and as such be in a position to place considerable constraints on the equation of state of dark energy.

In this presentation I will elucidate the connection between the contents of the universe and the observed number and masses of galaxy cluster through cosmic time. Following this I present briefly a rigorous likelihood framework for galaxy cluster cosmology developed by during my PhD at the University of Paris with Professor James G. Bartllett in collaboration with Dr. Jean-Baptiste Melin and Dr. Emmanuel Artis and forecasts on cosmological constraints for the Euclid mission with clusters of galaxies. This framework and cluster cosmology in general relies on robust weak lensing mass estimates of clusters. I will conclude by presenting measurements of weak lensing cluster masses using Hyper Suprime Cam weak lensing data on the Sloan Digitial Sky Survey DR8 redMaPPer cluster catalog. These mass estimates are obtained using an iterative matched filter method developed during this thesis which obtains masses for individual galaxy clusters.