Space is filled with tantalizing mysteries, but fast radio bursts, also known as “FRBs”, are perhaps the most elusive ones. These transient radio pulses come from far outside of the Milky Way Galaxy, and they last for about a thousandth of a second or a millisecond. However, sometimes these radio signals repeat. Though in most cases, the repetition occurs sporadically and without a regular pattern, a group of Canadian researchers has recently detected a signal that repeats regularly at an interval of 16.35 days. The radio pulses are coming from a galaxy located 500 million light-years away, and no one knows for sure what is causing them.

The signal was detected by the Max Planck Institute for Radio Astronomy, and the researchers used a specially designed radio telescope that is especially capable of detecting FRBs.

Fast radio bursts were first detected in 2007 using radio telescopes, which are designed to pick up radio waves instead of visible light. Though scientists have recorded dozens of FRBs over the years, none of them could be used to put together a compelling theory of their source. However, a group of Canadian researchers working with an especially high-tech radio telescope have been able to add an exciting piece to this complex puzzle. Between September 2018 and October 2019, they were able to detect 28 FRBs, one of which showed very regular patterns.

The radio signal was detected once every hour for a period of four days, and then it would stop only to resume 12 days later. The same cycle repeated at an interval of 16.35 days, and it continued on for over a year. The peculiar bursts originated in a massive spiral galaxy that is located about 500 million light-years away.

The way the signal repeats every 16 days can give us an insight into its origin. Scientists have already proposed a few theories as to what might be causing the mysterious FRB.

The Canadian Hydrogen Intensity Mapping Experiment collaborated with the Fast Radio Burst Project to publish a new paper that explores a few possible explanations behind this particular radio signal. According to the scientists, the periodicity of the signal is not mere coincidence. In fact, the 16-day cycle is a clue that can tell us about the source. So far, the experts are sure that the signal is not the product of a cataclysmic event such as a supernova, which is a one-time event. Beyond that, they do not have anything conclusive.

One possibility is that the signal is the result of orbital motion. Since celestial bodies orbit each other on regular timescales, two objects, such as a black hole and a star, could explain the 16-day cycle. On the other hand, since the signal is coming from the outskirts of the galaxy, the presence of a supermassive black hole is unlikely. They could very well be lower-mass black holes.

The authors also propose that a neutron star could be generating the radio pulses, but the waves are getting blocked when it is eclipsed by another object. This hypothesis could also explain the periodicity.

Although some would like to believe that the radio signal is coming from an alien civilization, scientists have rejected that theory.

Whenever we hear about strange radio waves reaching Earth, a part of us wonders whether it is aliens trying to communicate with us. As exciting as that sounds, it is very unlikely that this particular FRB is being sent by some otherworldly beings. That is because these radio waves are the result of extreme cosmological events, which are unlikely to be produced, even by a highly intelligent alien race. Moreover, scientists are yet to detect patterns that would suggest otherwise. 1,2,3