Hubble Space Telescope Traces Source of Five Radio Bursts

Astronomers using the Hubble Space Telescope have pinpointed the positions of some Fast Radio Bursts in a recent survey (FRBs). FRBs are strong energy jets of elusive, unknown sources until recently. The research team, which included Alexandra Manning and Sunil Simha of the University of California, Santa Cruz, and Wen-fai Fong of Northwestern University, surveyed eight FRBs and discovered that five of them originated from a spiral arm in their host galaxies.

FRB sources are notoriously difficult to find because the bursts are short and seldom repeat, making follow-up observations extremely difficult. In 2007, the first FRB was spotted (though searching through archival data revealed that an FRB had been captured in July 2001 by the Parkes radio observatory in Australia). A thousand of them have been discovered in the last two decades, but only about 15 have confirmed their source.

The best explanation for the origin of FRBs is that they are formed by energy outbursts from magnetars, based on the evidence so far. Magnetars are a type of neutron star (extremely dense stellar cores leftover from supergiant star collapse) named for their strong magnetic fields. This new study adds to the magnetar hypothesis by ruling out the possibility of other FRB sources.

The discovery that FRBs appear to occur along galactic spiral arms, for example, suggests that FRBs are unlikely to be caused by the eruption of massive young stars, which cluster in lighter regions of galaxies. It also rules out the merger of two neutron stars as an FRB source since such events occur well away from spiral arms and in far older galaxies. Magnetars, on the other hand, can easily exist inside the galactic spiral arms observed by Hubble Space Telescope.