Astronomers have discovered unusual signals coming from the centre of our galaxy. 

Using the CSIRO ASKAP telescope in Western Australia, researchers have detected a very unusual variable radio signal from towards the heart of the Milky Way. 

The radio waves fit no currently understood pattern of variable radio source and could suggest a new class of stellar object.

“The strangest property of this new signal is that it has a very high polarisation. This means its light oscillates in only one direction, but that direction rotates with time,” said Ziteng Wang, a PhD student at the University of Sydney and author of a new paper on the findings. 

“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 star emit variable light across the electromagnetic spectrum. Pulsars, supernovae, flaring stars and fast radio bursts are all types of astronomical objects whose brightness varies. With the huge advances in radio astronomy of recent years, the study of variable or transient objects in radio waves is revealing the secrets of the Universe. 

“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,” Mr Wang said.

The discovery of the object has been published in the Astrophysical Journal.

Mr Wang’s co-supervisor, Professor David Kaplan from 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.

“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,” Professor Murphy said. 

“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.”