Astronomers have discovered a peculiar radio signal originating from deep space that eludes current scientific understanding. Designated ASKAP J1935+2148, the signal repeats every 53.8 minutes, making it the longest period ever recorded for such a phenomenon.
Published in the magazine Astronomy of Naturethe discovery, made using the Australian Square Kilometer Array Pathfinder (ASKAP) radio telescope, has left astronomers both puzzled and excited about the potential implications for our understanding of the universe.
In recent years, astronomers have identified several enigmatic objects that emit repetitive radio signals. in 2020, GLEAM-X J162759.5-523504.3located near the galactic center, it was observed emitting extremely bright flashes for just three months before going 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 behaves a little differently.
The signal was first detected during routine observations by the ASKAP radio telescope, located in Australia’s Wajarri Yamaji state. The telescope, known for its wide field of view, was monitoring a gamma-ray burst when it collided with ASKAP J1935+2148. The signal was distinguished because of its unique properties, including its long period and distinct emission states.
ASKAP J1935+2148 on and off. (Image: Emil Lenc, CC BY-NC)
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 very unusual to detect a neutron star candidate emitting radio pulses in this way,” she said in a press release. “The fact that the signal is repeating at such a smooth rate is remarkable.”
After the initial discovery, the team conducted further observations over several months using ASKAP and the more sensitive MeerKAT radio telescope in South Africa.
Equipped with a special type of radio receiver, the ASKAP telescope was deployed in a grid pattern to scan the sky at a frequency of 887.5 MHz. The signals it received were split 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 in a higher frequency range (0.86-1.71 GHz), provided more detailed and sensitive observations.
“What’s intriguing is how this object exhibits three distinct emission states, each with completely different properties than the others,” Caleb explained. “The MeerKAT radio telescope in South Africa played a crucial role in distinguishing between these states. If the signals weren’t coming from the same point in the sky, we wouldn’t have believed it was the same object producing these different signals.”
According to the study, astronomers observed bright linear pulses that lasted anywhere between 10 and 50 seconds, followed by fainter pulses that followed a circular pattern lasting only 370 milliseconds, followed by a lull where no pulse was discernible. All this would happen again later.
This mysterious new radio signal challenges current astrophysical models of neutron stars and white dwarfs. Neutron stars, known for their rapid rotation, typically complete rotations in seconds or fractions of a second. The 53.8 minute period of ASKAP J1935+2148 places it in the “pulsar valley of death”, where no detectable radio signals are expected. In other words, if this is a neutron star, it shouldn’t give anything away.
One hypothesis is that ASKAP J1935+2148 may be an ultra-long-period magnetar, a type of highly magnetized neutron star. However, slow rotation and continuous radio emission are unusual for such objects. Another possibility is a highly magnetized white dwarf, but no known white dwarf has been observed to emit radio waves in this way, making this explanation less likely.
Caleb and her team currently believe that this radio signal is probably from a slow-rotating neutron star or a binary system with a neutron star or another white dwarf. They admit that this is only a hypothesis as something like this has never been observed before and further research needs to be done.
“It may even prompt us to reexamine 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.