Since they were first discovered in 2007, fast radio bursts (FRBs) have bemused astronomers. These brief but bright flashes of radio waves have been picked up by several telescopes, but their origin remained a mystery. Now, for the first time, we know for sure that they are coming from the distant universe.
It might seem like a strange discovery to herald, but FRBs have caused controversy in the past. Last year, several similar signals were found to be the result of scientists opening and closing a microwave oven door in a facility’s break room. Confirming they are an astrophysical phenomenon allows us to further investigate what might be producing them – something we still don’t know.
“They’re not from our galaxy, not our atmosphere, not our microwave ovens. They’re definitely from the distant universe,” Dr. Simon Johnston, from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia, and a member of the research team, told IFLScience.
A paper describing the discovery, named FRB 150418, on April 18, 2015, is published in this week’s Nature. Using a combination of the Parkes radio telescope in Australia, the CSIRO’s Compact Array telescope 400 kilometers (250 miles) north of Parkes, and the Japanese Subaru Telescope in Hawaii, the astronomers found a flash that originated in an unnamed galaxy 6 billion light-years away. The burst itself lasted just one millisecond, but it produced an afterglow that lasted six days, allowing its position to be located.
The signal was detected in an elliptical galaxy 6 billion light-years away. David Kaplan and Dawn Erb
And this afterglow actually allows us to narrow down what might be causing FRBs. According to Johnston, previous models such as giant pulses from pulsars can be ruled out. Instead, the favored explanation at the moment is merging binary stars, perhaps neutron stars.
Interestingly, merging binary stars are also one proposed source of detectable gravitational waves, following the signal found by LIGO from two merging black holes. If FRBs are produced in this way, it’s possible we could detect an FRB and gravitational waves from the same source at the same time. “This one is probably a little bit distant for LIGO to see, but yes in principle it would be very exciting if we got gravitational waves and a fast radio burst,” said Johnston.
Only 17 FRBs have been found so far, but it’s thought there are many, many more out there waiting to be discovered; estimates suggest up to 10,000 per day in our sky. This itself poses a problem, though, as we don’t expect stars to be merging this often. “It’s a surprisingly big number, it’s a bit of a puzzle,” said Johnston. It may be that there are multiple types of FRBs from different sources.
Another important discovery made off this observation is the resolution of the “missing baryon problem,” which concerns how there seems to be matter missing from the universe, according to our theories. From this FRB detection though, scientists found a delay between the signal arriving at high frequencies and low frequencies. This suggests the light was slowed down by matter between galaxies, invisible in optical light.
“The good news is our observations and the model match – we have found the missing matter,” said lead author Dr. Evan Keane in a statement.
Yes, that’s a lot of science from just one detection. But it shows just how important FRBs might be. While their origin and number remain uncertain, they are proving to be a fascinating phenomenon. At the moment, an FRB can be found once every 20 days using the Parkes telescope, but future observatories like the Square Kilometer Array (SKA) could increase this to several a week.
“We think FRBs will be useful to do tests of cosmology, and that’s pretty exciting, not only for us but the astro community in general,” added Johnston.