Scientists hunting for origin of radio signal from deep space that flashes for an hour

Western Australia

Scientists in Australia have discovered an unusual radio signal coming from space. The strange radio signal flashes for almost an hour, which is the longest ever seen till date. Upon several observations, it was also found that radio signal was emitting long, bright flashes of weak but fast pulses, and sometimes nothing at all. The team of scientists is yet to find an explanation for the surprising phenomenon.

It is not unusual to detect a radio signal afar our planet as astronomers usually see a lot of radio wave bursts originating from across the vast expanse of the universe, which they call radio transients. These radio transients are erupting in the universe every now and then, some in patterns and some just flicker once. 

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As per researchers, most of these radio transients come from rotating neutron stars known as pulsars. They emit regular flashes of radio waves, just like some cosmic lighthouses. Typically, these neutron stars spin at incredible speeds, taking mere seconds or even a fraction of a second to complete each rotation. But the recently discovered radio signal (or transient) had an hour long cycle, making it a rare appearance.

Search for the origin of longest radio signal continues

The team of researchers at the Wajarri Yamaji Country in Western Australia named the newly-found periodic radio transient ASKAP J1935+2148. The numbers in the name point to the location of the radio signal in the sky which was found using the CSIRO’s ASKAP radio telescope.

Using ASKAP, the team simultaneously monitored a source of gamma rays and searched for pulses from a fast radio burst, when the ASKAP J1935+2148 were spotted. The signal leapt out because it was made up of “circularly polarised” radio waves, which means the direction of the waves corkscrews around as the signal travels through space.

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Further observation revealed that ASKAP J1935+2148 belongs to the relatively new class of long-period radio transients. Only two others have ever been found, and ASKAP J1935+2148’s 53.8 minute period is by far the longest.

The origin of the signal which has such a long period of appearance remains a profound mystery, says the team. One possibility is that it is a slow-spinning neutron star. However, the object being a white dwarf cannot be ruled out. A white dwarf is an Earth-sized cinder of a burnt-out star that has exhausted its fuel.

White dwarfs often have slow rotation periods, but the team doesn't know of any way one could produce the radio signals of this intensity. What’s more, there are no other highly magnetic white dwarfs nearby, which makes the neutron star explanation more plausible.

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One explanation might be that the object is part of a binary system in which a neutron star or white dwarf orbits another unseen star.

"Further research is needed to confirm what the object is, but either scenario would provide valuable insights into the physics of these extreme objects", wrote team in their research paper.

The research was published in Nature Astronomy.

(With inputs from agencies)