The origin of these bright, millisecond long flashes of light is unknown because bursts or FRBs are unpredictable and disappear quickly. Scientists first observed them in 2007. In the following decade, they observed only about 140 bursts across the entire universe.
“The thing about FRBs is that they’re really hard to catch,” said Kiyoshi Masui, assistant professor of physics at MIT and a member of the university’s Kavli Institute for Astrophysics and Space Research. “You have to have your radio telescope pointed at the right place at the right time, and you can’t predict where or when it will be.”
Most radio telescopes only see a patch of sky the size of the moon at a given time, which means the vast majority of FRBs are not seen, Masui said.
That all changed when the CHIME telescope, located at the Dominion Radio Astrophysical Observatory in British Columbia, Canada, began receiving radio signals in 201
The stationary radio telescope, called the Canadian Hydrogen Intensity Mapping Experiment, discovered 535 new fast radio bursts between 2018 and 2019.
Not only does the catalog expand the known number of fast radio bursts, but it also expands the available information about their locations and properties. While most of the fast radio bursts occurred once, 61 of them repeated fast radio bursts from 18 sources. The repeated bursts look different – each flash lasts a little longer than the individual bursts.
When a burst is repeated, researchers have a much better chance of tracing it back to its place of origin. These locations can help researchers determine what is also causing the eruptions.
Based on their observations, the researchers believe that fast radio bursts may have sources that are different from repeated ones.
“With all these sources, we can really begin to get a picture of what FRBs look like as a whole, what astrophysics might drive these events, and how they can be used to study the universe in the future,” said Kaitlyn Shin, CHIME member and a graduate student at the Massachusetts Institute of Technology’s Department of Physics, in a statement.
This is how CHIME works
The CHIME telescope works a little differently than others used for radio astronomy. The matrix with four giant radio antennas comparable to the size and shape of half-tubes used for snowboarding is completely immobile. As the earth rotates on its axis, this matrix receives radio signals from half of the sky.
Typically, radio bowls move to capture light from different areas of the sky. Instead, CHIME uses a fully digital design and has a correlator, a digital signal processor to capture incoming radio signals. It can churn through huge amounts of data – approx. 7 terabit pr. Second or equivalent to a small percentage of global Internet traffic.
“Digital signal processing is what enables CHIME to reconstruct and ‘see’ in thousands of directions simultaneously,” Masui said. “That’s what helps us detect FRBs thousands of times more often than a traditional telescope.”
The 535 bursts discovered by CHIME came from all parts of the sky – and space. Based on the information they gathered, the scientists calculated that these bright fast radio bursts are likely to occur about 800 times a day across the sky.
“It’s such a beautiful thing about this field – FRBs are really hard to see, but they are not uncommon,” Masui said. “If your eyes could see radio flashes like you can see camera flash, you would see them all the time if you just looked up.”
While these bursts would be exciting enough based on their mysterious nature alone, scientists believe they can use bursts to gain a better understanding of the universe and even map the distribution of gas over it.
As these radio waves move through space, they are likely to encounter gas or plasma. This can distort the waves, change their properties and even their trajectory. Determining this information about a radio burst can help scientists estimate the distance, the distance traveled, and how much gas it encountered.
“This carries a record within it of the structure of the universe that it has traveled through on its way to get from the source to us,” Masui said. “Because of this, we believe they will be the ultimate tool for studying the universe.”
Many of these bright radio eruptions discovered by CHIME traveled from distant galaxies and were probably created by incredibly energetic sources – but scientists are still trying to determine the exact nature of these sources.
With enough rapid radio eruptions, it may be possible to map the large structure of the universe.
“These large structures make up the filaments of the cosmic web,” said Alex Josephy, a doctoral student in physics at McGill University in Canada. “With the FRB catalog, we have registered this connection between FRBs and large structure. This is really, really exciting and heralds a new era of (fast radio burst) cosmology.”