Fast radio bursts and superluminous supernovae: a surprising connection?

Fast radio bursts (FRBs) are one of the hottest topics in astrophysics right now. FRBs are millisecond pulses of extraterrestrial radio emission that had us all baffled for most of the last decade. In the past year however, astronomers have discovered the first “repeater” (an FRB source emitting multiple bursts over 4 years and counting), and localised this repeater to a host galaxy (making it the first FRB to be shown definitively to originate outside of our own Galaxy). Not only did this distant galaxy prove that FRBs must be extremely energetic, but the galaxy itself was very interesting: a puny dwarf galaxy with a low metal content. If FRBs come from some kind of star or stellar remnant, statistically they should live in galaxies with a lot of stars, not faint dwarf galaxies, so this was a surprising find. However, one stellar phenomenon known to occur only in galaxies just like this one is in fact the one closest to my heart: superluminous supernovae (SLSNe). Increasingly, the evidence indicates that SLSNe form highly magnetised neutron stars, or magnetars. These magnetars are expected to release flares, which could power FRBs if the flaring lasts long enough for some of them to escape the supernova debris. Inspired by these host galaxy and theoretical links, my colleagues and I have written this paper comparing the expected magnetar birth rates from SLSNe and other phenomena to the number of FRB sources in the sky. We found that SLSNe make enough magnetars to power all the observed FRBs, as long as these magnetars remain active for decades to centuries. This is especially nice because this timescale is longer than the minimum for FRBs to escape the supernova, but not too long that the magnetars should have long since run out of energy! So while far from certain, it is entirely feasible that SLSNe make FRBs. If we find just a couple more FRBs in dwarf galaxies, this picture will start to look more and more convincing, so stay tuned!

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