Penn State astronomers have discovered that the mysterious “cosmic whistles” known as fast radio bursts can pack a serious punch, in some cases releasing a billion times more energy in gamma-rays than they do in radio waves and rivaling the stellar cataclysms known as supernovae in their explosive power. The finding, published Nov. 11 in Astrophysical Journal Letters, is the first-ever finding of non-radio emission from any fast radio burst. It drastically raises the stakes for models of fast radio bursts and is expected to further energize efforts by astronomers to chase down and identify long-lived counterparts to fast radio bursts using X-ray, optical, and radio telescopes.
Fast radio bursts, or FRBs, were first discovered in 2007. Since then radio astronomers have detected a few dozen of these events. Although they last mere milliseconds at any single frequency, their great distances from Earth, and large quantities of intervening plasma, delay the arrival of their lower frequency components, spreading the signal out over a second or more and yielding a distinctive downward-swooping “whistle” across the typical radio receiver band.
“This discovery revolutionizes our picture of FRBs, some of which apparently manifest as both a whistle and a bang,” said coauthor Derek Fox, a Penn State professor of astronomy and astrophysics. The radio whistle can be detected by ground-based radio telescopes, while the gamma-ray bang can be picked up by high-energy satellites like NASA‘s Swift mission. “Rate and distance estimates for FRBs suggest that, whatever they are, they are a relatively common phenomenon, occurring somewhere in the universe more than 2,000 times a day.”
Efforts to identify FRB counterparts began soon after their discovery but have all come up empty until now. In its new study, the Penn State team, led by physics graduate student James DeLaunay, reported bright gamma-ray emissions from the fast radio burst FRB 131104, named after the date it occurred, Nov. 4, 2013. “I started this search for FRB counterparts without expecting to find anything,” said DeLaunay. “This burst was the first that even had useful data to analyze. When I saw that it showed a possible gamma-ray counterpart, I couldn’t believe my luck!”