Science

Strange radio signals from the centre of the galaxy

radio signals
Strange noises: astronomers are perplexed by a mysterious signal coming from the centre of the galaxy. Source: Luminas_Art (via Pixabay)

By Mia Becker-Hansen | Head of Science and Technology

Astronomers are baffled by strange radio signals emerging from the centre of the galaxy last week. They seem to turn on and off at random… the source must be from something never observed before.

The source, ASKAP J173608.2-321635, has been nicknamed ‘Andy’s object’, after the man who first discovered the radio waves at the University of Sydney, Australia. He and his colleagues have been monitoring the source since last year, detecting it a total of seventeen times using the Australian Square Kilometre Array Pathfinder radio telescope pointed towards the centre of our galaxy. Further observations have also been made using the MeerKAT radio telescope in South Africa.

Researchers found that the object flared up for periods of weeks before going dark again. The polarisation of the received radio waves suggests that the object probably has a strong magnetic field. Due to the object not being visible in any other wavelength, several known objects were ruled out as the possible source, such as a star or magnetar (neutron stars with very powerful magnetic fields). “We’ve looked at every other wavelength we can,” says David Kaplan at the University of Wisconsin-Milwaukee, “all the way from the infrared to optical to X-rays, and we see nothing, so it doesn’t seem to be consistent with any kind of star that we understand.”.

During flare periods the brightness of the source varied by up to a factor of 100, and they generally lasted for short periods of times, sometimes even as fast as a single day, suggesting that the object is small. “It’s an interesting object that has confounded any attempt we have to explain it,” continued Kaplan, “It could turn out to be part of a known class of objects, just a weird example, but that’ll push the boundaries of how we think those classes behave.”.

Could this object be aliens trying to communicate with us? Many have speculated so. However, Professor Tara Murphy from the University of Sydney’s Institute for Astronomy observed that it is highly unlikely. “[The source has] a lot of properties that mean we know they must be from something astronomical.” she says, “For example the radio emission is what we call broadband – it covers a very wide range of frequencies, and this could not be generated by an artificial source.”. While astronomers cannot confirm what is causing the signals, they are confident it is from a natural, astronomical source.

The new object appears to have some parallels with an emerging class of mysterious objects known as Galactic Centre Radio Transients (GCRTs), which are flashing radio signals that originate from near the galactic centre. Despite the parallels, there are properties of the signal which differ to those of GCRTs. This all adds more to the mystery as GCRTs themselves are not fully understood yet anyway.

The scientists will now bank upon the transcontinental Square Kilometre Array radio telescope, that will make sensitive maps of the sky every day to find out what the mysterious blinking object really is.

Mia Becker-Hansen Science and Technology

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