A study of dark subclusters found by weak lensing

We propose to observe three rich clusters of galaxies tolook for significant dark subclusters that are not seen in opticalimages but are inferred from weak lensing mass maps. Our candidatescome from the largest weak lensing study yet of 39 xray selectedclusters. Detecting these subclusters and measuring their propertieslike mass, temperature and metallicity would constitute the firstcomprehensive study of its kind, and provide important clues to thenature of stochastic biasing and galaxy formation. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]