Scientists have pinpointed the source of one of the bizarre fast radio bursts that have made its way to Earth.
FRBs are powerful flashes of radio waves lasting for mere milliseconds that come from beyond the galaxy. Around 80 of such intense radio events have been recorded by scientists over the years, but their origins have remained an enticing mystery.
Signals From A Distant Galaxy
Findings published in the journal Nature revealed that researchers at the Caltech's Owens Valley Radio Observatory discovered a new FRB called FRB 190523. Then, working with the W. M. Keck Observatory in Hawaii, the team traced its source to a faraway galaxy 7.9 billion light-years away.
According to study author and Caltech assistant professor Vikram Ravi, the team at OVRO developed a new array consisting of ten 4.5-meter dishes known as the Deep Synoptic Array-10. Collectively, these act as a mile-wide dish, capable of covering an area of the sky that's roughly the size of 150 full moons.
With the new array, the study authors discovered that the host galaxy of FRB 190523 is strikingly similar to the Milky Way, which is surprising given that another FRB has been traced to a host galaxy that forms stars a hundred times faster than the Milky Way. It challenges the theory that FRBs come from the eruption of plasma from young, extremely magnetic neutron stars known as magnetars.
"The theory that FRBs come from magnetars was developed in part because the earlier FRB 121102 came from an active star-forming environment, where young magnetars can be formed in the supernovae of massive stars," Ravi pointed out. "But the host galaxy of FRB 190523 is more mellow in comparison."
The Challenge Of Finding FRBs
It's only the third time that the source of a FRB has ever been identified, which is an important step in learning more about these strange signals and their causes. In 2017, FRB 121102 was found to come from a galaxy 3 billion light-years away. More recently in June 2019, researchers announced that they used the Australian Square Kilometer Array Pathfinder to trace FRB 180924 to a galaxy 4 billion light-years away.
FRB 121102 is the easiest to localize, because it has continued to burst every few weeks since it was discovered in 2014. Most FRBs just emit a single intense burst, including the ones recorded by OVRO and the Australian telescopes.
"Finding the locations of the one-off FRBs is challenging because it requires a radio telescope that can both discover these extremely short events and locate them with the resolving power of a mile-wide radio dish," Ravi explained.
Ravi and his team captured their discovery with their new array, but this array is only the first step in the planned Deep Synoptic Array. The DSA, which is slated to be completed in 2021, will eventually consist of 110 radio dishes.
"With the full Deep Synoptic Array, we are going to find and localize FRBs every few days," Gregg Hallinan, OVRO director and Caltech professor, revealed. "This is an exciting time for FRB discoveries."
