Scientists have been baffled after discovering a mysterious radio signal blasting toward Earth from an unknown source in the center of the Milky Way.
The unexpected discovery was made by researchers at the University of Sydney, using a powerful radio telescope in Western Australia. Although astronomers often discover unusual phenomena coming from the galactic core, the Sydney researchers have so far failed to explain their latest discovery.
The radio waves picked up by the Australian SKA Pathfinder (ASKAP) telescope do not appear to fit any known source of radio signals in space.
The researchers are now determined to find out exactly what is happening at the center of the galaxy, which is about 26,000 light-years from Earth.
Zhiting Wang, a doctoral student at the University’s College of Physics and lead author of a new study describing this phenomenon, revealed that the signal may indicate the existence of a new class of stellar objects.
He said, “The strangest feature of this new signal is that it has a very high polarization. This means that its light only oscillates in one direction, but that direction rotates over time.”
He added: “The brightness of the object also varies greatly, by a factor of 100, and the signal is turned on and off apparently randomly. We’ve never seen anything like it before.”
Stars of all kinds emit light that extends across the electromagnetic spectrum.
The spectrum covers all types of electromagnetic radiation, including visible light, X-rays, ultraviolet radiation, radio waves, and others.
Stellar objects such as pulsars, supernovae, fast radio bursts, and blazing stars have varying brightness.
But so far, none of these things have been able to explain the mystery signal.
“We initially thought it might be a pulsar – a very dense type of rotating dead star – or another type of star that emits massive solar flares,” Wang said. But the signals from this new source do not match what we expect from these types of celestial bodies.”
Tara Murphy, Wang’s PhD supervisor, added: “We have been scanning the sky with ASKAP to find new, unusual objects through a project known as Variables and Slow Transients (VAST), throughout 2020 and 2021. Looking at the galactic center, we find ASKAP J173608.2-321635, named after its coordinates. This thing was unique in that it started invisible, became shiny, faded, and reappeared.”
After the signal was originally detected using ASKAP, the radio waves were confirmed by the MeerKAT telescope of the South African Radio Astronomy Observatory.