Astronomers question their science after distant galaxy emits strange radio signals that ‘face the wrong way’

Representative image of the galaxy cluster MACS J0717

(X-ray: NASA/CXC/SAO/van Weeren et al.; Optical: NASA/STScI; Radio: NSF/NRAO/VLA)

The apple falls from the tree because gravity follows exact rules on our planet. We feel sleepy after eating rice because it helps release calming hormones in our body. In nature everything is organized and in its place. But once in a while, she likes to throw a spanner in the works, seemingly just to play with the confused scientists brave enough to study natural law.

That’s exactly the case with a particularly cheeky galaxy cluster called Abell 3266, whose latest strange outbursts have astronomers and physicists tearing their hair out and scurrying over their books to find some explanation for its strange behavior.

But before we get into the complicated (and beautiful) cosmic mess that is these galaxy clusters, let’s try to understand it in terms that are extremely familiar to everyone: fossils!

The fossils of ancient secular cities

We know that dinosaurs and other flora existed long before us because they left tangible evidence that we could study. In the same way that we could date these ancient fossils to determine exactly how old they were, scientists are also using similar techniques to study the radio emissions of supermassive black holes in space, which are essentially the “fossils” of these magnificent cosmic behemoths.

Radio emissions are a type of “invisible” light emitted by celestial bodies that radio astronomers study to understand their composition and age, among other things. His study reveals some of the universe’s most surprising and well-hidden secrets, such as the origin of the Big Bang through the study of the infamous cosmic microwave background radiation.

Much of what makes a cluster is plasma — a chaotic state of matter that forms when gas is heated in tubes to 10 million degrees Celsius. When radio waves are generated through this plasma, some familiar patterns emerge, which scientists categorize to gain insight into the galactic environment.

So what’s up with the Abell 3266?

While the abundant trace of many of these radio debris from colliding clusters and supermassive black holes remains elusive to us, their mere existence gives us fundamental answers to some simple questions. If there is a shadow, we know there is something opaque to cast it. But Abel, the cluster 800 million light-years away, was already an enigma because, although it met all the conditions, it cast no proverbial shadow!

The cluster had no detectable radiorelics until recently. And when Australian scientists tried to study it using the combined power of more than three separate powerful satellite arrays, they noticed that some of the highly elusive emissions challenged everything they thought they knew about them.

Radio emissions emanating from one part of the cluster formed an explosion-like sonic arc, likely fueled by shock waves traveling through the plasma from some massive cosmic disturbance. However, its highly unusual hollow shape puzzled the radio scientists, as they had never seen anything like it before. In addition, its odd orientation facing away from the center of the cluster earned it the nickname “false relic”.

“If it’s a shock wave, you might think it would bend like an arc around the edge, but this is turned,” explained one of the astrophysicists behind the study, Dr Tessa Vernstrom. “So we don’t really understand what this is telling us.”

A new type of science?

Dr. Wernstrom adds that her team believes this is real and likely not an error from image processing. In addition, the unexpected brightness of the relic also meant that there were huge gaps in our understanding of how these radiofossils behave, and that scientists had to go back to the drawing board to come up with explanations.

“Maybe there’s some kind of new physics going on that we don’t fully understand when our models can’t match the observations,” he added.

Colliding galaxy clusters, like some in Abell 3266, are scary places in space that leave scientists sniffling with excitement, but also send rattles to their bones. These environments have so much plasma and dark matter activity that they produce a whole variety of data that would otherwise be impossible to collect in a lab.

Abell 3266, in particular, is a special cluster because there are tons of anomalies and rarities that are absent from most other observed clusters or simply haven’t been detected yet. However, it also serves as a testament to the growing power of radio telescopes and the exciting opportunity to study the rest of the universe.

“Looking at radio, you see a kind of different physics than when you look at the other wavelengths,” explains Dr. Wernstrom. “We’re going to see a lot more of this kind of thing.”

The research was published in Monthly Notices of the Royal Astronomical Societyand you can access here.


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