Fast radio bursts (FRBs) are one of the most interesting phenomena discovered in the last decade. They are quick radio pulses lasting a few milliseconds that likely formed beyond the Milky Way, although we still don’t know what causes them.
Now, Penn State University researchers have discovered that FRBs can release a billion times more energy in the form of gamma-rays than observed in radio waves. The research was published in the Astrophysical Journal Letters, and focuses on FRB 131104, which occurred on November 4, 2013.
"I started this search for FRB counterparts without expecting to find anything," said lead author James DeLaunay in a statement. "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!"
This is the first FRB that has been observed in another wavelength, and the discovery was possible thanks to NASA’s Swift observatory that regularly scans the sky to catch X-ray and gamma-ray bursts. It was quite lucky that it was pointing at the right place at the right time.
"Although theorists had anticipated that FRBs might be accompanied by gamma rays, the gamma-ray emission we see from FRB 131104 is surprisingly long-lasting and bright," said co-author Derek Fox, a Penn State professor of astronomy and astrophysics.
The gamma-ray emission lasted between two and six minutes, which is many hundreds of times the length of FRB 131104. This, in combination with the gargantuan emission of energy in gamma-rays, suggests that FRBs must be caused by some catastrophic event.
"In fact, the energy and timescale of the gamma-ray emission is a better match to some types of supernovae, or to some of the supermassive black hole accretion events that Swift has seen," Fox added. "The problem is that no existing models predict that we would see an FRB in these cases."
The researchers suggest that in future detections of FRBs, there should be a rapid-response observation that could identify possible counterparts and hopefully provide us with some clues about the true nature of these objects.