One of the most puzzling phenomena in space may finally have an explanation. It might be caused by the interactions between a “dead” neutron star and a planet in tight orbit around it.
The strange phenomenon in question is a repeating fast radio burst (FRB). These are series of powerful radio waves blasting at us from distant galaxies. FRB 121102, spotted in 2012, was the first one ever found to repeatedly send out radio wave blasts. But there is something strange about these repeating FRBs.
“The leading candidates for driving such bursts are compact objects such as neutron stars and black holes, which are all spinning periodically,” says at Sun Yat-Sen University in China. As such, we would expect repeating FRBs to blast out signals regularly. But most – including FRB 1211012 – send out flashes at random intervals. “The lack of periodicity so far has deepened the mystery,” says Gao.
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Gao led a team that analysed observations from several telescopes of 1145 bursts from FRB 121102. There was no obvious pattern – until the researchers divided and categorised the bursts by energy. They then found that the highest-energy parts of the bursts did seem to follow a couple of periodic patterns – one that repeated every 157 days, and one that repeated every 4.6 days.
The researchers interpreted the longer pattern to mean the neutron star causing the bursts is probably orbiting another star every 157 days, which is disturbing the neutron star and changing its behaviour to produce the first signal. The shorter pattern, meanwhile, suggests the neutron star has a planet that circles it every 4.6 days, causing the second signal. This planet, if it exists, is probably only about 15 per cent as far from its star as Mercury is from the sun.
That would make this strange world extraordinarily unpleasant. “The magnetosphere of the planet will be unlikely to be able to handle the violent bombardment of high-energy particles from the neutron star and the harassment of the neutron star’s magnetic field,” says Gao. “The sky will not be blue, cannot have clouds, will not have beautiful rainbows – instead, [it would have] lightning all the time.”
However, there are some concerns about the existence of the planet. This is largely because the method used to find the patterns in the data from FRB 121102 was more convoluted than those that are usually used to search for periodicity in astronomical phenomena.
“If one chops up the data in a bunch of different ways, then there are more chances to find something that looks like a pattern,” says at the University of Amsterdam in the Netherlands. “The claim requires confirmation using a significantly larger set of data.” The researchers are working on adding more observations of FRB 121102 to their models now.
arXiv
