China’s humongous radio telescope has reaped an impressive harvest of special signals from a galaxy 3 billion light-years away. The signals, known as fast radio bursts (FRBs), are extremely short but very powerful emissions of radio waves. Even though we're still not sure what FRBs actually are, or where they come from, these particular signals were traced to emitter FRB 121102, one of the few FRBs that have been caught repeating.
The Five-hundred-meter Aperture Spherical Radio Telescope (FAST) has been scanning the patch of sky where FRB 121102 originates and was able to detect more than 100 signals between August 30 and the first few days of September. This is the highest number of bursts detected so far for this source, with 20 pulses observed on September 3 alone.
FRB 121102 is one of only 10 known FRBs and the first one to be discovered. The fact that it is repeating made it possible to find its origin, a dwarf galaxy 3 billion light-years from Earth, and its likely source, a neutron star moving through an incredibly powerful magnetic field. There are still uncertainties about how these bursts are produced, however, and much more data, like these observations FAST collected, is needed.
FAST is the most sensitive listening device in the world. The single-radio dish is built in the Dawodang depression, Guizhou province, south-west China and measures 600 meters (1,968 feet) across, making it the world's largest telescope. As of yesterday, the telescope is considered fully operational by Chinese scientists and has been submitted for a national review, where it will move from being an under-construction project to a full working facility.
"Once we pass this review, FAST becomes an accepted telescope for exploring the Universe,” JIANG Peng, FAST’s chief engineer and deputy director of FAST Operation and Development Center, NAOC, said in a statement. “FAST has been open to Chinese astronomers since April 2019. After the National Construction Acceptance, it will be open to astronomers across the world.”
FRBs are some of the most incredible astronomical events we have ever observed. They last for just a fraction of a second. Recent estimates suggest that maybe over 150 such events could be seen from Earth every day. Given than most of these are a one-off, finding them is just a matter of serendipity, looking at the right spot at the right time.
Detections of these events have increased in the last few years, and we are now also capable of following up the detection in real-time. We are yet to have a complete picture of FRBs but we are gaining more and more insight with each new observation.