Untangling a Galaxy Cluster Knot

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Produced by the Space Telescope Science Institute’s Office of Public Outreach in collaboration with NASA’s Universe of Learning partners: Caltech/IPAC, Center for Astrophysics | Harvard & Smithsonian, and NASA Jet Propulsion Laboratory.
Video imagery:

  • X-ray, radio, and optical/infrared composite image of Abell 2256. X-ray: Chandra: NASA/CXC/Univ. of Bologna/K. Rajpurohit et al.; XMM-Newton: ESA/XMM-Newton/Univ. of Bologna/K. Rajpurohit et al. Radio: LOFAR: LOFAR/ASTRON; GMRT: NCRA/TIFR/GMRT; VLA: NSF/NRAO/VLA; Optical/IR: Pan-STARRS
  • Radio images of Abell 2256: LOFAR/ASTRON; NCRA/TIFR/GMRT; NSF/NRAO/VLA

Writer: Leah Ramsay
Designer: Leah Hustak
Science review: Dr. Martha Irene Saladino 
Education review: Jim Manning
Music from Music for Non-Profits



A montage of outer space photos appears.
Title, News from the Universe
Text, Untangling a galaxy cluster knot. February 9, 2023. A photo shows a galaxy surrounded by blue light with red bursts of light on the outer edges.
Text, Astronomers across the globe are collaborating to study a huge mash-up of at least three galaxy clusters, together called Abell 22 56.
A line points to lighter areas in the center of the blue light.
Text, Multiple telescopes were used to get a picture of what is happening in the ongoing mega-cluster merger.
A line continues to point to lighter areas in the center of the blue light.
Text, The cluster contains an unusually large number of galaxies emitting radio waves.
Text, The radio waves show where particle jets are blasting away from supermassive black holes.
The blue light fades and the red line shows two jets connecting across the space.
Text, Some of the jets have impacted the merging clusters' hot gas and slowed down, creating complex shapes and filaments.
Dotted lines circle 5 irregular red shapes along the left edge.
Text, Huge filamentary structures were likely generated when the cluster collision created shock waves and accelerated particles in the gas across two million light years.
Dotted lines circle two larger shapes at the top right.
Text, A fainter halo of radio emission was detected near the center of the collision.
A dotted line circles a larger area at the center left. Text, Halo
The halo's properties present a new challenge for astronomers because their models can't explain all its observed features.
The still photo of the marked halo continues to appear.
Text, Abell 22 56 highlights the need for more theoretical study of galaxy cluster mergers.
This news was brought to you in part by the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA