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Repeating mysterious cosmic radio bursts detected

Thursday, Mar 3, 2016,17:25 IST By Metrovaartha A A A

Toronto | Astronomers have for the first time detected repeating short bursts of mysterious and powerful radio waves from an enigmatic source that is likely located well beyond the edge of our Milky Way galaxy.

The findings indicate that these fast radio bursts come from an extremely powerful object which occasionally produces multiple bursts in under a minute, researchers said. All previously detected fast radio bursts (FRBs) have appeared to be one-off events, they said. Because of that, most theories about the origin of these mysterious pulses have involved cataclysmic incidents that destroy their source  a star exploding in a supernova, for example, or a neutron star collapsing into a black hole.

The new finding, however, shows that at least some FRBs have other origins. FRBs, which last just a few thousandths of a second, have puzzled scientists since they were first reported nearly a decade ago. Despite extensive follow-up efforts, astronomers until now have searched in vain for repeat bursts.¬† Lat year, McGill University PhD student Paul Scholz was sifting through results from observations performed with the Arecibo radio telescope in Puerto Rico – the world’s largest radio telescope.

The new data run through a supercomputer showed several bursts with properties consistent with those of an FRB detected in 2012. The repeat signals were surprising  and very exciting, Scholz said. I knew immediately that the discovery would be extremely important in the study of FRBs, said Scholz. Scholz pored over the remaining output from specialised software used to search for pulsars and radio bursts. He found that there were a total of 10 new bursts.

The finding suggests that these bursts must have come from a very exotic object, such as a rotating neutron star having unprecedented power that enables the emission of extremely bright pulses, the researchers said. It is also possible that the finding represents the first discovery of a sub-class of the cosmic fast-radio-burst population. Not only did these bursts repeat, but their brightness and spectra also differ from those of other FRBs, said Laura Spitler, postdoctoral researcher at the Max Planck Institute for Radio Astronomy in Germany.

Scientists believe that these and other radio bursts originate from distant galaxies, based on the measurement of an effect known as plasma dispersion. Pulses that travel through the cosmos are distinguished from man-made interference by the influence of interstellar electrons, which cause radio waves to travel more slowly at lower radio frequencies. The 10 newly discovered bursts, like the one detected in 2012, have three times the maximum dispersion measure that would be expected from a source within the Milky Way.

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