MACS J0025.4-1222

MACS J0025.4-1222 is a galaxy cluster created by the collision of two galaxy clusters, and is part of the MAssive Cluster Survey (MACS). Like the earlier discovered Bullet Cluster, this cluster shows a clear separation between the centroid of the intergalactic gas (of majority of the normal, or baryonic, mass) and the colliding clusters.

In the image, intergalactic gas is shown in pink and the mass centroids of the colliding clusters in blue, showing the separation of the two, similar to the Bullet Cluster. It provides independent, direct evidence for dark matter and supports the view that dark matter particles interact with each other only very weakly.

Details

The shown image is a composite of separate exposures made by Hubble Space Telescope ACS and WFPC2 detectors and the Chandra ACIS detector. The Hubble images were taken on November 5, 2006, and June 6, 2007. The visible light images from Hubble allowed astronomers to infer the distribution of total mass (both dark matter and normal matter). With gravitational lensing Hubble was then able to map the dark matter (colored in blue). The distribution of normal matter (pink) is mostly in the form of hot gas glowing brightly in X-rays. Its distribution was accurately mapped from Chandra data.