Chandra Release - June 22, 2011

Visual Description: Abell 2744

The composite image of galaxy cluster Abell 2744 showcases an array of distant galaxies, hot gas and other celestial objects. The image features a vibrant pink and blue-purple hue, which is prevalent throughout the galaxy cluster, creating a captivating contrast against the dark blue background. At the center of the image, there is a large hot pink gaseous shape, almost like a mottled bird, diving into the more blue-purple nebulous area. The gaseous, nebulous shapes are littered with bright white-yellow pops of light, like too many holiday lights on a tree.  This object was created by one of the most complicated and dramatic collisions between galaxy clusters ever seen. It has been dubbed "Pandora's Cluster" because of the wide variety of different structures seen. Data from NASA's Chandra X-ray Observatory are colored pink-red, showing gas with temperatures of millions of degrees. In blue is a map showing the total mass concentration (mostly dark matter) based on data from the Hubble Space Telescope, the Very Large Telescope, and the Japanese Subaru telescope. Optical data also show the constituent galaxies of the clusters. The "core" region shows a slightly bullet shaped structure in the X-ray emitting hot gas (the diving bird) and a separation between the hot gas and the dark matter. This separation occurs because electromagnetic forces between colliding particles in the clouds of hot gas create a friction that slows them down, while dark matter is unaffected by such forces.