Hubble Survey Carries Out a Dark Matter Census
ScienceDaily (Oct. 13, 2011) — Cluster MACS J1206.2-0847 (or MACS 1206 for short) is one of the first targets 
in a Hubble survey that will allow astronomers to construct the highly detailed dark matter maps of more galaxy clusters than ever before. These maps are being used to test previous but surprising results that suggest that dark matter is more densely packed inside clusters than some models predict. This might mean that galaxy cluster assembly began earlier than commonly thought.