Something strange is sending radio waves from the center of the galaxy

Source of the signals are unknown and do not correspond to any known natural phenomena

An irregular radio source has been discovered in the direction of the galactic centre.
Illustration of radio waves coming from the galactic centreSebastian Zentilomo
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Strange radio signals are coming from the direction of the centre of the galaxy and we aren’t sure what is emitting them. They turn on and off seemingly at random, and their source must be unlike anything else we have seen before.

The source of this radiation has been nicknamed “Andy’s object” after Ziteng Wang at the University of Sydney in Australia, who goes by the name Andy and first discovered the radio waves. He and his colleagues spotted the emissions six times in 2020 using the Australian Square Kilometre Array Pathfinder radio telescope. They made further observations with the MeerKAT radio telescope in South Africa.

The researchers found that the object occasionally flared for up to a few weeks, but was dark most of the time. When it finally lit up again in February this year, several months after the initial detection, they pointed some of the most powerful non-radio telescopes we have at it and saw nothing. “We’ve looked at every other wavelength we can, 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,” says David Kaplan at the University of Wisconsin-Milwaukee, who was part of the research team.

The fact that it wasn’t visible in any other wavelengths ruled out several possible explanations for this object, including normal stars and magnetars, which are neutron stars with powerful magnetic fields.

Whatever Andy’s object is, the polarisation of the radio waves coming from it indicates that it probably has a strong magnetic field. During flares, its brightness varied by up to a factor of 100, and those flares faded extraordinarily quickly – as fast as a single day – facts that suggest the object is small.

But no astronomical body we know of fits all of those strange traits. “It’s an interesting object that has confounded any attempt we have to explain it,” says 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.”