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Strange radio waves are coming from the center of our galaxy

Astronomers from the University of Sydney have recently detected a very unusual radio signal coming from the direction of the center of our galaxy. These radio waves fit no currently understood pattern of variable radio source and could be emitted by a previously unknown class of stellar object.

The research team discovered the object using CSIRO’s ASKAP radio telescope in Western Australia.  “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,” said study senior author Tara Murphy, a professor in the School of Physics at the University of Sydney. 

“Looking towards the center 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 behavior was extraordinary.”

Follow-up observations were made with the more sensitive South African Radio Astronomy Observatory’s MeerKAT telescope. However, these further observations still did not manage to completely clarify the nature of the mysterious object emanating the radio waves.

“The strangest property of this new signal is that it is has a very high polarisation. This means its light oscillates in only one direction, but that direction rotates with time,” said study lead author Ziteng Wang. “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.”

Many types of stellar objects, including pulsars, flaring stars, supernovae, and fast radio bursts, emit variable light across the electromagnetic spectrum. The newly discovered object appears to be similar with a class of stellar objects called Galactic Center Radio Transients.

“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’,” explained David Kaplan, an associate professor of Physics at the University of Wisconsin-Milwaukee.

“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 aim to continue the observation of the object in the following years, and hopefully understand more about its nature and properties.

The study is published in The Astrophysical Journal.

By Andrei Ionescu, Staff Writer

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