Radio Signal From Space Repeats Every Hour, Defying Explanation

An anonymous reader quotes a report from New Atlas: The universe is awash with strange radio signals, but astronomers have now detected a really bizarre one that repeats every hour, cycling through three different states. While they have some ideas about its origin it can't be explained by our current understanding of physics. The signal first appeared in data gathered by the ASKAP radio telescope in Australia, which watches a big swath of sky at once for transient pulses. Officially designated ASKAP J1935+2148, the signal seems to repeat every 53.8 minutes. Whatever it is, the signal cycles through three different states. Sometimes it shoots out bright flashes that last between 10 and 50 seconds and have a linear polarization, meaning the radio waves all 'point' in the same direction. Other times, its pulses are much weaker with a circular polarization, lasting just 370 milliseconds. And sometimes, the object misses its cue and stays silent.

So what could be behind such a weird radio signal? Let's get it out of the way up front: it's not aliens (probably). The most likely explanation, according to the scientists who discovered it, is that it's coming from a neutron star or a white dwarf. But it's not a neat solution, since the signal's weird properties don't fit with our understanding of the physics of those two kinds of objects. Neutron stars and white dwarfs are fairly similar, but with some key differences. They're both born from the deaths of bigger stars, with the original mass dictating whether you end up with a neutron star or a white dwarf. Neutron stars are known to blast radio waves out regularly, so they're a prime suspect here. It's possible that signals this varied could be produced by interactions between their strong magnetic fields and complex plasma flows. But there's a major problem: they usually spin at speeds of seconds or fractions of a second per revolution. It should be physically impossible for one to spin as slow as once every 54 minutes. White dwarfs, on the other hand, would have no problem spinning that slowly, but as the team says, 'we don't know of any way one could produce the radio signals we are seeing here.' 'It might even prompt us to reconsider our decades-old understanding of neutron stars or white dwarfs; how they emit radio waves and what their populations are like in our Milky Way galaxy,' added Caleb.

The findings have been published in the journal Nature Astronomy.

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