A multi-wavelength composite image from several orbiting and ground-based telescopes captures an ongoing cosmic collision between at least four galaxy clusters, each containing hundreds of galaxies. The region is collectively known as Abell 2744, approximately 4 billion light-years from Earth.
Composite image of the Abell 2744 region, with radio, X-Ray, and optical data combined. Image credit: Pearce et al / Bill Saxton / NRAO / AUI / NSF / Chandra / Subaru / ESO.
The collisions in Abell 2744 generated shock waves that set off a celestial fireworks display of bright radio emission, seen as red and orange.
In the center of the image, the purple indicates X-rays caused by extreme heating.
The radio portion of the image comes from new observations made with NSF’s Karl G. Jansky Very Large Array, and is combined with earlier data from NASA’s Chandra X-ray observatory.
Both are overlaid on an image at visible-light wavelengths made with data from NAOJ’s Subaru telescope and ESO’s Very Large Telescope (VLA).
The VLA observations revealed previously undetected regions where shocks accelerated subatomic particles, causing radio emission.
Connor Pearce of the Harvard-Smithsonian Center for Astrophysics and colleagues are studying the combined image in an attempt to decipher the sequence of collisions.
“Currently, evidence indicates a North-South (top-bottom in the image) collision of subclusters and an East-West (left-right in the image) collision,” the astronomers said.
“There is a possible third collision, and we continue to analyze our data to uncover more details about the region’s complex history of collisions and their aftermath.”
The team’s findings are published in the Astrophysical Journal.
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C.J.J. Pearce et al. 2017. VLA Radio Observations of the HST Frontier Fields Cluster Abell 2744: The Discovery of New Radio Relics. ApJ 845, 81; doi: 10.3847/1538-4357/aa7e2f
