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Scientists detect mysterious radio signal from heart of Milky Way galaxy

Scientists say the radio waves fit no currently understood pattern.

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By Stephen Beech via SWNS

An "extraordinary" signal emerging from the heart of the Milky Way is intriguing scientists.

They say the radio waves fit no currently understood pattern — and could even suggest a new class of stellar object.

Scientists say the object may be related to another mysterious celestial object known as the "cosmic burper."

Study lead author Ziteng Wang said: “The strangest property of this new signal is that it is has a very high polarization.

"This means its light oscillates in only one direction, but that direction rotates with time.

“The brightness of the object also varies dramatically, by a factor of 100, and the signal switches on and off apparently at random. We’ve never seen anything like it.”

He explained that many types of star emit variable light across the electromagnetic spectrum.

With massive advances in radio astronomy, the study of variable or transient objects in radio waves is a huge field of study helping to reveal the secrets of the universe.

Pulsars, supernovae, flaring stars and fast radio bursts are all astronomical objects whose brightness varies.

The discovery was revealed in the Astrophysical Journal.

Wang, a Ph. D. student in the School of Physics at the University of Sydney, Australia, said: “At first we thought it could be a pulsar - a very dense type of spinning dead star - or else a type of star that emits huge solar flares.

"But the signals from this new source don’t match what we expect from these types of celestial objects."

Wang and an international team, including scientists from Australia’s national science agency CSIRO, the United States, Canada, South Africa, Germany Spain and France discovered the object using CSIRO's ASKAP radio telescope in Western Australia.

Night winter snow-covered mountain ridge in Moon light pastel illumination and starry Milky Way in sky (Ukraine, Carpathian Mountains, Svydovets Range, Blyznytsja Mount).
A photo of the Milky Way galaxy as seen from Earth. (Photo by Sun Shock via Shutterstock)

Follow-up observations were made with the South African Radio Astronomy Observatory’s MeerKAT telescope.

Professor Tara Murphy, Wang’s PhD supervisor, said: “We have been surveying the sky with ASKAP to find unusual new objects with a project known as Variables and Slow Transients (VAST), throughout 2020 and 2021.

“Looking towards the centre of the Galaxy, we found ASKAP J173608.2-321635, named after its coordinates.

"This object was unique in that it started out invisible, became bright, faded away and then reappeared. This behaviour was extraordinary.”

After detecting six radio signals from the source over nine months last year, the astronomers tried to find the object in visual light. But they found nothing. They turned to the Parkes radio telescope and again failed to detect the source.

Professor Murphy said: “We then tried the more sensitive MeerKAT radio telescope in South Africa.

(Photo by Kendall Hoopes via Pexels)

"Because the signal was intermittent, we observed it for 15 minutes every few weeks, hoping that we would see it again.

“Luckily, the signal returned, but we found that the behaviour of the source was dramatically different - the source disappeared in a single day, even though it had lasted for weeks in our previous ASKAP observations.”

However, the further discovery did not reveal much more about the secrets of this transient radio source.

Professor David Kaplan, Wang’s co-supervisor of the University of Wisconsin-Milwaukee, said: “The information we do have has some parallels with another emerging class of mysterious objects known as Galactic Centre Radio Transients, including one dubbed the ‘cosmic burper.'

“While our new object, ASKAP J173608.2-321635, does share some properties with GCRTs there are also differences. And we don’t really understand those sources, anyway, so this adds to the mystery.”

The scientists plan to keep a close eye on the object to look for more clues as to what it might be.

Professor Murphy added: “Within the next decade, the transcontinental Square Kilometre Array (SKA) radio telescope will come online.

"It will be able to make sensitive maps of the sky every day.

“We expect the power of this telescope will help us solve mysteries such as this latest discovery, but it will also open vast new swathes of the cosmos to exploration in the radio spectrum.”

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