spaceSpace and Physics

This Image Shows A Massive Galaxy Pile-Up 4 Billion Light-Years Away


Jonathan O'Callaghan

Senior Staff Writer

The composite image of Abell 2744. Pearce et al.; Bill Saxton, NRAO/AUI/NSF; Chandra, Subaru; ESO.

This awesome image shows the collision of several galaxy clusters, each with hundreds of galaxies inside, taking place 4 billion light-years away.

The image is the result of a collaboration between three observatories: the Very Large Array (VLA) in New Mexico, the Very Large Telescope (VLT) in Chile, and NASA’s Chandra X-ray space observatory. A paper in the Astrophysical Journal, led by the Harvard-Smithsonian Center for Astrophysics, describes these findings.


Using these different observatories allowed astronomers to combine radio, X-ray, and visible light into a single composite image. This has highlighted a number of interesting features taking place in this galaxy cluster.

For one thing, we can see various shock waves moving through the region, generating a “celestial fireworks display” of bright radio emissions according to the National Radio Astronomy Observatory (NRAO). These are seen as the red and orange bands in the image above.

In the middle of the image, there is a purple region, which is the result of X-rays caused by extreme heating, seen by Chandra. Thanks to the VLA, we’ve also been able to see previously undetected regions where some of the shocks are accelerating subatomic particles, causing even more radio emissions.

Radio-only image of Abell 2744. Pearce et al., NRAO/AUI/NSF

Studying the combined image could tell us more about how galaxy cluster collisions take place. There appears to be a collision occurring between the top and bottom, and another between the left and right of the region. There may also be a third collision hidden in the area.


The Abell 2744 galaxy cluster has been looked at before in the Hubble Frontier Fields project, because it’s an interesting massive cluster that acts as a lens to more distant galaxies. It’s thought that four smaller galaxy clusters have come together here over 350 million years, giving rise to the current view we see today.

It’s also known as Pandora’s Cluster, because of the different and strange phenomena unleashed by the start of the collision. This has produced some strange effects that we haven’t see elsewhere, and it’s likely this region of space will be studied even more in future.

Now with these latest images, we’ve got a new fascinating look at what’s taking place in this corner of the universe.


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