Recently, astronomers have picked up a puzzling radio signal that cycles through three different states and repeats every hour from space. Officially known as ASKAP J1935+2148, this odd signal was initially discovered in data collected by the Australian radio telescope ASKAP, which searches wide areas of the sky for brief pulses. Experts are baffled by the signal’s regularity, which repeats every 53.8 minutes and defies existing scientific knowledge.
ASKAP J1935+2148 cycles through three different emission states. At times, it emits bright flashes lasting between 10 and 50 seconds with linear polarization, where the radio waves align in the same direction. Other times, the pulses are weaker, exhibit circular polarization, and last just 370 milliseconds. Occasionally, the signal goes silent altogether, missing its usual cue.
Dr. Manisha Caleb, the lead author of the study, highlighted the uniqueness of this object. “What is intriguing is how this object displays three distinct emission states, each with properties entirely dissimilar from the others,” she said. The MeerKAT radio telescope in South Africa was instrumental in differentiating these states. According to Dr. Caleb, if the signals hadn’t originated from the same point in the sky, it would have been hard to believe they were from the same object.
The origin of this perplexing signal is currently a topic of speculation among scientists. While the possibility of it being an alien signal is unlikely, the leading hypothesis is that it comes from a neutron star or a white dwarf. However, this explanation is not without its problems. The signal’s characteristics do not align well with our current understanding of the physics governing these celestial objects.
Neutron stars and white dwarfs share some similarities but also have critical differences. Both result from the death of larger stars, with the original star’s mass determining whether a neutron star or white dwarf forms. Neutron stars typically emit regular radio waves, making them a prime suspect. However, the slow repetition rate of 54 minutes is problematic, as neutron stars usually spin much faster. White dwarfs can spin more slowly, but there is no known mechanism for them to produce the observed radio signals.
This mystery is reminiscent of a similar repeating radio signal found a few years ago on an 18-minute loop, which also seemed impossible under known physical laws. The complexity and duration of ASKAP J1935+2148 deepen the enigma, suggesting that there may be unknown processes at play.
Whether this signal originates from an unusual neutron star, an elusive “white dwarf pulsar,” or something entirely different, further observations are needed to unravel the mystery. Dr. Caleb suggests that this discovery might even challenge our long-held understanding of how neutron stars and white dwarfs emit radio waves and their prevalence in the Milky Way galaxy.
