Astronomers Detect A Mysterious Signal Coming From the Galaxy's Core And It 'Fits No Currently Understood Pattern'

The University of Sydney reported that astronomers uncovered a mystery signal originating from the galaxy's core that "fit no currently understood the pattern of the variable radio source and could suggest a new class of stellar object."

Initially, astronomers thought the signal came from a pulsar (a star that spins extremely fast) or a huge solar flare. Closer examination revealed that the newly discovered source's emissions do not match those of known stars. They reported their results in the Astrophysical Journal.

"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," Ziteng Wang, lead author of the new study and a Ph.D. student in the School of Physics at the University of Sydney, explained in a statement. "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."

Wang and a team of international researchers spotted the object using the CSIRO's ASKAP radio telescope. The South African Radio Astronomy Observatory's MeerKAT telescope conducted more observations. The crew was seeking new objects in space as part of research called variables and slow transients (VASTs). 

"Looking towards the center of the galaxy, we found ASKAP J173608.2-321635, named after its coordinates," said Wang's Ph.D. supervisor Professor Tara Murphy. "This object was unique in that it started invisible, became bright, faded away, and then reappeared. This behavior was extraordinary."

The scientists discovered six radio signals from the source during nine months in 2020. But when they tried to find the item in visible light, they found nothing.

Though the astronomers cannot currently categorize the strange radio signal source, Wang's co-supervisor, Professor David Kaplan from the University of Wisconsin-Milwaukee, said there are "some parallels with another emerging class of mysterious objects known as galactic center radio transients, including one dubbed the 'cosmic burper." 

Radio transients, with their short bursts of radio signals, are often signals for unusual astronomical events. In September, for example, astronomers from Caltech revealed their findings on radio transient signals that came from a black hole prematurely triggered a star to go supernova.

The ASKAP J173608.2-321635 radio signal's discoverers anticipate that additional observations may reveal the source's mystery. "Within the next decade, the transcontinental Square Kilometer Array (SKA) radio telescope will come online. It will be possible to generate daily sensitive sky maps "Prof. Murphy said. That new telescope may help solve the enigma, but it may also reveal new mysteries hidden in the cosmos.