Astronomers have detected a peculiar radio signal originating from deep space that eludes current scientific knowledge. The signal, designated ASKAP J1935+2148, repeats every 53.8 minutes, making it the longest period ever recorded for such a phenomenon.
Published in the magazine Nature AstronomyThe discovery, made using the Australian Square Kilometer Array Pathfinder (ASKAP) radio telescope, has amazed and excited astronomers about its potential implications for our understanding of the universe.
In recent years, astronomers have identified several enigmatic objects that emit repeating radio signals. In 2020, GLEAM-X J162759.5-523504.3located near the galactic center, it emitted unusually bright flashes for only three months before falling silent.
Another object, discovered last year, GPM J1839-10behaves like a slow pulsar, emitting five-minute radio bursts every 22 minutes.
However, the newly discovered radio signal works slightly differently.
The signal was first detected during routine observations by the ASKAP radio telescope, located in Australia’s Wajarri Yamaji Country. The telescope, known for its wide field of view, was monitoring a gamma-ray burst when it encountered ASKAP J1935+2148. The signal stood out for its unique properties, including its long period and different emission states.
Dr. Manisha Caleb, an astrophysicist at the University of Sydney and lead author of the study, said in a press release that she thinks this could be a new type of neutron star.
“It is highly unusual to discover a candidate neutron star that emits radio pulsations in this way,” she said a press release. “The fact that the signal repeats itself at such a leisurely pace is extraordinary.”
After the initial detection, the team carried out further observations over several months with both ASKAP and the more sensitive MeerKAT radio telescope in South Africa.
Equipped with a special type of radio receiver, the ASKAP telescope was arranged in a grid pattern to scan the sky at a frequency of 887.5 MHz. The signals it picked up were divided into smaller pieces to get a clearer picture, and the data was processed every 10 seconds to capture the bright pulses from ASKAP J1935+2148. Meanwhile, the MeerKAT telescope, which operates at a higher frequency range (0.86-1.71 GHz), provided more detailed and sensitive observations.
“What’s intriguing is how this object exhibits three different emission states, each with properties completely different from the others,” Caleb explains. “The MeerKAT radio telescope in South Africa played a crucial role in distinguishing these states. If the signals did not come from the same point in the sky, we would not have believed that it was the same object producing these different signals.”
According to the study, the astronomers observed bright linear pulses that lasted between 10 and 50 seconds, followed by fainter pulses that followed a circular pattern that lasted only 370 milliseconds, followed by a lull in which no pulses were detectable. This would all repeat itself.
This new mysterious radio signal challenges current astrophysical models of neutron stars and white dwarfs. Neutron stars, known for their rapid rotation, typically complete their rotations in seconds or fractions of a second. The 53.8 minute period of ASKAP J1935+2148 places it in the ‘pulsar death valley’, where no detectable radio signals are expected. In other words, if this is a neutron star, it shouldn’t be giving off anything.
One hypothesis is that ASKAP J1935+2148 could be an ultra-long period magnetar, a kind of highly magnetized neutron star. However, the slow rotation and persistent radio emission are unusual for such objects. Another possibility is a highly magnetized white dwarf, but white dwarfs have not been observed to emit radio waves in this way, making this explanation less likely.
Caleb and her team currently believe that this radio signal likely comes from a slowly spinning neutron star or a binary star system with a neutron star or another white dwarf. They admit that this is just a hypothesis as nothing like this has ever been observed before and further research needs to be done.
“It might even prompt us to rethink our decades-old understanding of neutron stars or white dwarfs,” Caleb concluded. “How they emit radio waves and what their populations are like in our Milky Way Galaxy.”
MJ Banias covers space, security and technology with The Debrief. You can email him at mj@thedebrief.org or follow him on Twitter @mjbanias.