Galaxy clusters are smashing together to form ‘flaming cosmic narwhal’

Hundreds of millions of light years away, a group of galaxy clusters are locked in a deadly dance. At least three clusters are in the process of smashing together, forming a single colossal cluster called Abell 2256.

Some astronomers have taken to calling it the “flaming cosmic narwhal” because of the horn-like appearance of some of the jets in the system and the glowing tufts of radio waves at the top of the image. Researchers have used six of the most powerful observatories to unravel what is going on in the wisps and whorls of this chaotic mega-cluster.

Each telescope captured a different part of the strange and complex structure. Two X-ray observatories imaged the hot gas, which glows blue in this image. Stars, shining white and yellow in the image, were caught in optical and infrared wavelengths of light.

Radio waves are shown in red in the picture, and they come from a variety of different sources. The straight slashes of red are jets blasting away from the supermassive black holes at the centres of galaxies, whereas the red swirls and squiggles come from jet material smashing into the surrounding gas. The filaments near the top of the image – the “flames” of the cosmic narwhal – stretch across about 2 million light years, and most likely come from the cosmic collision itself, which created shock waves that roiled through the cluster.

But despite all this stunning detail, there are questions about Abell 2256 that remain unanswered: there is a faint halo of radio waves near the centre of the cluster that hasn’t been fully explained yet, and it contains more galaxies that emit radio waves than we would expect. Researchers are still working to analyse the smorgasbord of data and figure out the details of how enormous clusters like this one are formed.

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