Clash Of Clusters Provides New Dark Matter Clue

August 27, 2008

Hubble and Chandra Composite of the Galaxy Cluster MACS J0025.4-1222. (Credit: NASA, ESA, CXC, M. Bradac (University of California, Santa Barbara), and S. Allen (Stanford University))

New Hubble and Chandra observations of the cluster known as MACSJ0025.4-1222 indicate that a titanic collision has separated dark from ordinary matter. This provides independent confirmation of a similar effect detected previously in a target dubbed the Bullet Cluster, showing that the Bullet Cluster is not an anomalous case.

MACSJ0025 formed after an enormously energetic collision between two large clusters. Using visible-light images from Hubble, astronomers were able to infer the total mass distribution — dark and ordinary matter. Hubble was used to map the dark matter (coloured in blue) using a technique known as gravitational lensing.

Chandra data enabled the astronomers to accurately map the ordinary matter, mostly in the form of hot gas, which glows brightly in X-rays (shown in pink).

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Posted in Science and Technology, Space Exploration