New, Unexplained Extra-Galactic Signals Found

Every now and then we detect an unusual signal from outer space that we have never seen before. Initially we can’t explain them, which is understandable; they’re a new type of signal and you can’t go around making up nonsense just because you don’t understand something. At least, scientists don’t. In 1967 Dame Jocelyn Bell Burnell was the first to detect a pulsar, a highly magnetised, incredibly dense type of pulsating star (hence pulsar) that, at the time, had no explanation. Playfully, that night they called the signal LGM-1 for Little Green Men. As new data came in, though, the real explanation presented itself and a new kind of star was discovered, work for which, scandalously, Burnell Bell’s supervisor but not Burnell Bell herself received a Nobel Prize.

Recently another new signal has been detected for which we currently have no explanation. They are called Fast Radio Bursts (FRB) and are, well, fast bursts of radio waves. In this context fast is anywhere from a quarter to a sixth of a millisecond. There have been about a dozen detected over they years, the first in 2001, and all bar one were seen at the Parkes Radio Telescope (PRT) in Australia. The reason I’m writing about this now is that five new FRBs have been detected in quick succession at the PRT; interestingly, one of them was different to all the others that had ever been detected.

Right now we really don’t know what causes them but, with this new data, we are now able to refine our theories. The previous leading theory was that they could have been caused by two massive objects, like blackholes or neutron stars, colliding. One of the new FRBs, though, was actually a double burst separated by just 2.4 milliseconds; this is thought to rule out the massive body collision theory as they don’t collide twice. The only other clues we have to go on are an observation from 2012 that confirmed suspicions that their origins were extra-galactic, and, due to the dispersal of their frequency range, we know they have travelled through an ionised plasma which is basically the stuff from which stars are made.

These features distinguish them from Perytons which are very similar to FRBs but have a terrestrial origin. There are various phenomena which can cause Perytons one of which, and I’m not kidding about this, is the microwave in the Parkes telescope kitchen. If you open the door before the timer has finished the telescope can detect it. So, whether in jest or otherwise, before you go writing LGM on your findings it might be best to make sure no one is having lunch first.

Although published only recently in arXiv (open access) the signals were found in data from 2012. It’s likely we’ll need plenty more such observations before we finally pin down precisely what is causing this particular phenomenon.

Image courtesy of Ian Sutton

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