By Heidi Hecht | @Squidgoo
How rare is a repeating FRB? Fast Radio Bursts (FRBs) were first detected in 2007 precisely because they’re difficult to spot. It’s also difficult to pinpoint the source of an FRB because they come and go so quickly. A radio telescope has to be pointed in the right direction at the right time to detect these intense bursts of radio waves that last for only a fraction of a second. As a result, it’s unusual to pick up an FRB more than once or have multiple radio telescopes pointed in the right place at the right time to pick one up.
In fact, repeating FRBs such as the recently detected FRB 121102 may not be all that rare. Only 18 FRBs of any type have been detected since 2007, but scientists estimate that detectable FRBs may occur once every ten seconds. FRB 121102 is simply the first repeating FRB that has been detected and pinpointed in a small galaxy three billion years from Earth.
“This dwarf galaxy has fewer stars [than large galaxies like the Milky Way] but is forming stars at a high rate, which may suggest that FRBs are linked to young neutron stars,” said Shriharsh Tendulkar, a postdoctoral researcher at McGill University in Montreal.
It had been assumed that larger galaxies would have more FRBs because they have more neutron stars. Arecibo Observatory in Puerto Rico first discovered FRB 121102 in 2012 and spotted it again in 2014, and then the Very Large Array observed this FRB flashing nine times during a study in 2016. The Gemini North telescope followed up with a study of the region to determine the source. The accumulated data on this FRB suggests that the neutron star producing these intense bursts of radio waves may be a pulsar, or a rotating neutron star that periodically sends beams of light directly at Earth as it spins.
Tendulkar indicated that other extreme events known to happen at a higher rate in dwarf galaxies include long-duration gamma ray bursts and superluminous supernovas. “This discovery may hint at links between FRBs and these two kinds of events.”
Other astronomers were more cautious, hinting that this FRB may have a different source than most, based on the observation of a steady source of radio waves coming from the same region of the sky. What makes an FRB like this one different from ambient radio waves detected in the night sky, though, is that these brief bursts of radio waves can contain more energy than our sun will release in 10,000 years.
Papers based on the studies of FRB 121102 will be published in the journal Nature and The Astrophysicist Journal Letters.