Fast radio bursts are one of the many mysteries astronomers tackle every day. Also called FRBs, they are bright radio flashes that last just milliseconds. Detecting FRBs is a challenge. Pinpointing their location is even more difficult.
Did you know: The first fast radio burst was discovered in 2007, and only 17 have been discovered so far.
“In the past FRBs have been found by sifting through data months or even years later. By that time it is too late to do follow-up observations,” Evan Keane, lead author of the new research, said in a statement.
A new system was needed. An international team of scientists developed one called the SUrvey for Pulsars and Extragalactic Radio Bursts, or SUPERB. It can detect FRBs within seconds. Once detected, an alert goes out to telescopes around the world to search the area where the FRB originated from. Remember, previous FRBs were spotted by looking through old data. With SUPERB, telescopes can look for evidence of the FRB just after the milliseconds-long flash.
On April 18, 2015, a fast radio burst was detected and an alert sent out.
Using CSIRO’s Australia Telescope Compact Array (ATCA), astronomers observed the radio afterglow for nearly six days before it faded. These observations let them pinpoint its source nearly 1,000 times more precisely than previous FRBs.
ATCA helped, but they still didn’t know which galaxy the FRB came from. That’s where the 8.2-meter Subaru optical telescope in Hawaii comes in. The telescope identified the source as an elliptical galaxy. Using the redshift measurement (which gives astronomers the distance travelled by an FRB), scientists found the galaxy is 6 billion light-years away.
The fast radio burst is located in a galaxy in the cyan circle. The right panel shows the Subaru telescope zooming in on the exact galaxy.
Michael Kramer, from the Max Plank Institute for Radio Astronomer, said the FRB was caused by “a cataclysmic event.”
What do these new FRB measurements tell us?
So, location and distance. Doesn’t seem like ground-breaking science, does it? For FRBs, they are. Before this new research, all astronomers had to work on what an FRB’s frequency-dependent dispersion. It’s a delay in the radio signal caused by the material it passes through.
Simon Johnston, the co-author of the study, explains why the new measurements are so important. “Until now, the dispersion measure is all we had. By also having a distance we can now measure how dense the material is between the point of origin and Earth, and compare that with the current model of the distribution of matter in the Universe,” said Johnston. “Essentially this lets us weigh the Universe, or at least the normal matter it contains.”
Our current understanding is that the Universe is made up of 70% dark energy, 25% dark matter and 5% ‘ordinary’ matter. The ordinary matter is the star stuff we can see. Dark energy and dark matter continue to be mysteries. There were even questions about the ordinary matter. Astronomers could only account for about 50% of ordinary matter. But, there’s good news about the other 50% of the missing matter.
“The good news is our observations and the model match, we have found the missing matter,” says Keane. “It’s the first time a fast radio burst has been used to conduct a cosmological measurement.”
What’s next for FRB detection?
More. Scientists want more detections and more precise measurements. The more we know about FRBs, the more we know about how matter is distributed in the Universe. Scientists found the missing ‘ordinary’ matter. Maybe one day they can shed more light on the mysteries of dark energy and dark matter.