Clusters of galaxies are the largest interconnected structures in the Universe gravity… They can contain thousands of galaxies, huge oceans of hot gas, invisible islands dark matter and – sometimes – the glowing ghost of one or two jellyfish.
The galaxy cluster Abell 2877, located in the southern sky, contains about 300 million. light years from Earth, astronomers have discovered one such jellyfish. The cosmic jelly, visible only in a narrow band of radio light, is over 1 million light-years across and includes a large petal of supercharged plasma from which tentacles of hot gas flow down.
The jelly-like appearance of the structure is both “ghostly” and “eerie,” according to the authors of a new article published on March 17 in Astrophysical Journal… Even more surprising than the cosmic jelly shape, however, the authors say, is how quickly the structure disappears from view.
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“This radio jellyfish is sort of a world record holder,” says study lead author Torrance Hodgson of the International Center for Radio Astronomy Research (ICRAR) in Perth, Australia. said in a statement… “Although the usual FM radio is bright radio frequencies, at 200 megahertz radiation almost disappears. No other extragalactic radiation has been observed to disappear so quickly anywhere near. “
Ghost of the jellyfish of the past
The universe is filled with energy structures that are only visible in radio waves, like a mysterious X-shaped galaxies a cart in space, or double drops at the center of the Milky Way. However, such a large structure in such a narrow band of the radio spectrum has not yet been observed.
According to the researchers, this likely means that this space jellyfish is actually a strange bird known as the “radio phoenix.”
Like a mythical bird that died in a fire and was resurrected again from the ashes, the radio phoenix is a cosmic structure born from a high energy explosion (for example, black hole flare), dims over millions of years as the structure expands and its electrons lose energy, and then finally gains new energy as a result of another cosmic cataclysm (for example, a collision of two galaxies).
To create a radio phoenix, this latest cosmic event must be powerful enough to send shock waves propagating through the sleeping cloud of electrons, causing the cloud to collapse and the electrons to burst into energy again. According to the study authors, this could cause a structure such as a cluster of jellyfish to glow brightly in some radio waves, but quickly dim in others.
“Our working theory is that about 2 billion years ago, a handful of supermassive black holes from several galaxies spewed powerful jets plasma, “Hodgson said.
The energy of this plasma disappeared over millions of years, until “two things happened very recently – the plasma started mixing simultaneously with the passage of very soft shock waves through the system,” Hodgson said. “This briefly reignited the plasma, illuminating the jellyfish and its tentacles for us to see.”
The researchers used computer simulations to show that this explanation is a plausible story about the origin of this large jellyfish in the sky, although several important questions, such as where the “soft shock waves” came from, remain unanswered. The team hopes to become more familiar with jellyfish in the future, following the completion of the Square Kilometer Array, a network of hundreds of radio telescope antennas planned to be built in the Australian outback.
Originally published on Live Science.