Galaxy clusters are the most important constructions within the universe certain collectively by gravity. They will include 1000’s of galaxies, huge oceans of sizzling gasoline, invisible islands of darkish matter and — generally — the glowing ghost of a jellyfish or two.
Within the galaxy cluster Abell 2877, situated within the southern sky about 300 million light-years from Earth, astronomers have found one such jellyfish. Seen solely in a slim band of radio mild, the cosmic jelly is greater than 1 million light-years large and consists of a big lobe of supercharged plasma, dripping with tentacles of sizzling gasoline.
The construction’s jelly-like look is each “ghostly” and “uncanny,” in line with the authors of a brand new paper printed March 17 within the Astrophysical Journal. Nevertheless, much more astonishing than the house jelly’s form is how shortly the construction vanishes from view, the authors mentioned.
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“This radio jellyfish holds a world document of types,” lead research writer Torrance Hodgson, of the Worldwide Centre for Radio Astronomy Analysis (ICRAR) in Perth, Australia, mentioned in a press release. “While it is vivid at common FM radio frequencies, at 200 megahertz the emission all however disappears. No different extragalactic emission like this has been noticed to vanish wherever close to so quickly.”
The ghost of jellyfish previous
The universe is swimming with energetic constructions which are solely seen in radio wavelengths, just like the mysterious X-shaped galaxies cartwheeling by means of house, or the twin blobs on the heart of the Milky Approach. Nevertheless, no construction this massive has ever been noticed in such a slim band of the radio spectrum.
In line with the researchers, that probably means this cosmic jellyfish is definitely an odd hen referred to as a “radio phoenix.”
Just like the legendary hen that died in flame and rose once more from the ashes, a radio phoenix is a cosmic construction that is born from a high-energy explosion (like a black gap outburst), fades over thousands and thousands of years because the construction expands and its electrons lose power, then lastly will get reenergized by one other cosmic cataclysm (such because the collision of two galaxies).
To create a radio phoenix, that final cosmic occasion have to be highly effective sufficient to ship shockwaves surging by means of the dormant cloud of electrons, inflicting the cloud to compress and the electrons to spark with power once more. In line with the research authors, that might trigger a construction just like the jellyfish cluster to glow brightly in sure radio wavelengths, however dim quickly in others.
“Our working principle is that round 2 billion years in the past, a handful of supermassive black holes from a number of galaxies spewed out highly effective jets of plasma,” Hodgson mentioned.
That plasma’s power light over thousands and thousands of years, till “fairly lately, two issues occurred — the plasma began mixing similtaneously very mild shock waves handed by means of the system,” Hodgson mentioned. “This has briefly reignited the plasma, lighting up the jellyfish and its tentacles for us to see.”
The researchers used a pc simulation to indicate that this rationalization is a believable origin story for that large jellyfish within the sky, although a number of large questions — similar to the place the “mild shockwaves” got here from — stay unanswered. The workforce hopes to take a more in-depth take a look at the jellyfish sooner or later, following the completion of the Sq. Kilometre Array — a community of lots of of radio telescope antennas deliberate for development within the Australian Outback.
Initially printed on Stay Science.