Dr. Wang Ziteng, a PhD student in physics at the University of Sydney, combed through data collected by the ASKAP radio telescope in Australia at the end of 2020. The data contained about 2 million objects, and what they had to do was classify each one.
Computers have identified most of the stars, and where they are currently. But an object in the center of the Milky Way has squashed computers and researchers.
The object sent out six radio signals in nine months in 2020. This signal irregularity and polarization of radio emissions are not like anything researchers have seen before.
Even stranger, they couldn't find the object in X-rays, visible light, or infrared light. Although listening to it for several months with two different radio telescopes, nothing was found.
About a year after the signal was first discovered, it suddenly reappeared and then disappeared again.
"Unfortunately, we can't determine what object emitted this signal from," Murphy, a team of researchers at the University of Sydney, said during an interview with Insider.
It is becoming increasingly clear that the objects that emit such signals are absolutely not the same as the other 2 million objects that have been classified.
"That's when we started getting excited," Murphy said.
The team sent their data to other radio astronomers for help. Little by little, they confirmed that no one had ever found anything like it before.
The researchers concluded that this mysterious signal from the galactic center may have originated from the "Galactic Center Radio Transient (GCRT). Only three such signals have been found before.
Murphy was convinced that the signal wasn't coming from aliens, because the technical signal would use a narrower frequency range, much like a human radio station.
GCRT has been a mystery for decades. And each GCRT is not exactly the same, leading the researchers to believe that the four signals did not come from the same type of object.
Telescopes first began observing the center of the Milky Way galaxy at low frequencies on radio in the 1990s. But it wasn't until early 2000, when Hyman's team studied data from such low-frequency radio telescopes, that a strange signal was first discovered.
Initially the signal strength is high, then fades over the course of several months. Unlike other transient radio signals, no signs are left in X-ray observations.
and his colleagues discovered the first GCRT. Within three years, the team found another one. It emits a radio signal every 77 hours and then disappears.
These are very "bright" signals, which means they emit powerful radio waves. believes that if they continue their search, they will find more GCRT, including darker or weaker ones.
"We think we're at the tip of the iceberg," said Heyman, who is currently retired and has worked as a professor and researcher in physics at sweet Briar College. "We expect that given that the first one is easy to find, we will find more."
In about 10 years of searching, they found only one GCRT. They re-observed the universe with a very large array of radio telescopes, but no more signals appeared.
Wang and Murphy may have finally found another GCRT, but their discovery didn't provide much clue as to what these mysterious objects might be.
Researchers have theories about GCRT, but none of them are very satisfactory.
GCTs can be neutron stars or pulsars that orbit each other in groups of two or three, so radio signals from one star are obscured by other stars at irregular intervals. They could also be dead pulsars — running out of energy — and emitting irregular radio signals.
believes there are other undiscovered GCRTs, some of which are obscured by thick dust that permeates the galactic center.
The new observatory is better able to monitor the center of the Milky Way than the observatory Heyman used in the 2000s. Whenever the U.S. Naval Research Laboratory released new observations of the Galactic Center, he scanned them for signs of GCRT. Murphy's team plans to continue listening to the galactic center with ASKAP while looking for signs of mysterious objects in X-rays, visible or infrared light.
Heyman said the matrix radio telescope currently under construction in Australia and South Africa will be more capable of detecting GCRT than any previous radio observatory. It is scheduled to be completed in 2028.
"I really hope we can re-examine these three objects and figure out what they are," Heyman said. "They may be lurking in a very dim, stationary state. They may now be very faint, but can still be detected with very sensitive instruments. ”