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USS Jellyfish emits strange radio waves

Science desk || shiningbd

Published: 15:22, 28 March 2021  
USS Jellyfish emits strange radio waves

Low-frequency radio waves (red, orange, yellow, white) outline a huge “jellyfish,” 1.2 million light-years across, in galaxy cluster Abell 2877

Something’s fishy in the southern constellation Phoenix.

Strange radio emissions from a distant galaxy cluster take the shape of a gigantic jellyfish, complete with head and tentacles. Moreover, the cosmic jellyfish emits only the lowest radio frequencies and can’t be detected at higher frequencies.

The unusual shape and radio spectrum tell a tale of intergalactic gas washing over galaxies and gently revving up electrons spewed out by gargantuan black holes long ago, researchers report in the March 10 Astrophysical Journal.

Spanning 1.2 million light-years, the strange entity lies in Abell 2877, a cluster of galaxies 340 million light-years from Earth. Researchers have dubbed the object the USS Jellyfish, because of its ultra-steep spectrum, or USS, from low to high radio frequencies.

“This is a source which is invisible to most of the radio telescopes that we have been using for the last 40 years,” says Melanie Johnston-Hollitt, an astrophysicist at Curtin University in Perth, Australia. “It holds the record for dropping off the fastest” with increasing radiofrequency.

Johnston-Hollitt’s colleague Torrance Hodgson, a graduate student at Curtin, discovered the USS Jellyfish while analyzing data from the Murchison Widefield Array, a complex of radio telescopes in Australia that detect low-frequency radio waves.

These radio waves are more than a meter long and correspond to photons, particles of light, with the lowest energies. Remarkably, the USS Jellyfish is about 30 times brighter at 87.5 megahertz — a frequency similar to that of an FM radio station — than at 185.5 MHz.