Neutron Star In Stellar Nursery Could Be The Cause Of A Repeating Fast Radio Burst

Artist's impression of a Magnetar's outburst. NASA's Goddard Space Flight Center

Astronomers have found only a couple of dozen fast radio bursts (FRBs) – extragalactic radio emissions that last for only a handful of milliseconds. Out of those, only one has been observed repeating more than once.

That signal, known as FRB 121102, is believed to be caused by a neutron star, and new research seems to support the idea. Researchers have looked at the galaxy that hosts FRB 121102 using the Hubble Space Telescope. They found that the signal seems to be coming from a stellar nursery. This suggests that the source of the radio signal is a stellar object, rather than a supermassive black hole.

The research is currently being peer-reviewed and has been submitted to the Astrophysical Journal Letters. There’s also another study, in the same stage of submission to the Astrophysical Journal, that looked at the galaxy that hosts FRB 121102. The second study used the Subaru Telescope in Hawaii to work out the properties of the galaxy, which is located 2.4 billion light-years away.

The galaxy is an irregular object, so it's neither spiral nor elliptical, and is relatively small at only 20,000 light-years across – about one-fifth of the Milky Way. Both studies show that the galaxy is forming new stars at a prolific rate for its tiny size.  

The star-forming region where FRB 121102 originates is located on the outskirts of the galaxy, 6,200 light-years from the core. The stellar nursery is about 4,400 light-years in diameter, a lot larger than anything we have in our own galaxy.

The researchers think that FRB 121102 is generated by a neutron star, a compact object bigger than the Sun but compressed to only 20 kilometers (12 miles) across. The neutron star is believed to have a strong magnetic field, which accelerates particles around it and sends the millisecond radio wave pulses as repeated FRBs.

The type of neutron stars known as magnetars form when a massive star reaches the end of its life, but it’s not massive enough to turn into a black hole. The star goes supernova and leaves behind a collapsed core of degenerate matter – the neutron star. In star-forming regions, massive stars are the first to form and the first to die, so it’s not a surprise that FRB 121102 is located there.

Although this explanation fits well the characteristics of FRB 121102, more observations are necessary to confirm it. Also, this cannot be applied to your generic FRBs. These signals remain mysterious, and although we have narrowed down the list of potential suspects, we have yet to confirm the true culprit.

[H/T: New Scientist]

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