The origins of these brilliant millisecond flashes of light are unknown because bursts, or FRBs, are unpredictable and quickly disappear. Scientists first observed them in 2007. Over the next decade, they observed only about 140 bursts across the universe.
“The problem with 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 just the right place at the right time and you can’t predict where or when it will be.”
Most radio telescopes only see a moon-sized patch of sky at any given time, which means the vast majority of FRBs are not visible, 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 2018 during its first year of operation.
The stationary radio telescope, called the Canadian Hydrogen Intensity Mapping Experiment, detected 535 new rapid radio bursts between 2018 and 2019.
Not only does the catalog expand on the known number of rapid radio bursts, it also expands the information available on their locations and properties. While most of the rapid radio bursts occurred once, 61 of them repeated rapid radio bursts from 18 sources. Repeated bursts appear differently – each flash lasts a little longer than single bursts.
When a burst repeats, scientists have a much better chance of tracing it back to its point of origin. These locations could also help scientists determine the causes of the bursts.
Based on their observations, the researchers believe that single rapid radio bursts may have different sources than repeating ones.
“With all of these sources, we can really start to get a sense of what FRBs look like as a whole, what astrophysics might be behind these events, and how they can be used to study. universe in the future, “said Kaitlyn Shin, CHIME member. and a graduate student in the physics department at the Massachusetts Institute of Technology, in a statement.
How CHIME works
The CHIME telescope works a little differently from other telescopes used for radio astronomy. The array of four giant radio antennas, comparable to the size and shape of halfpipes used for snowboarding, is completely still. When the Earth rotates on its axis, this network receives radio signals from half the sky.
Typically, satellite dishes move to capture light from different areas of the sky. Instead, CHIME uses an all digital design and has a correlator, a digital signage processor to capture incoming radio signals. It can generate massive amounts of data – around 7 terabits per second, or the equivalent of a small percentage of global Internet traffic.
“Digital signal processing is what allows CHIME to simultaneously reconstruct and ‘look’ in thousands of directions,” Masui said. “It’s what helps us detect FRBs a thousand times more often than a traditional telescope. “
The 535 bursts detected by CHIME came from all parts of the sky and space. Based on the information they gathered, the researchers calculated that these rapid and bright radio bursts likely occur around 800 times a day across the sky.
“That’s kind of the beautiful thing about this area – FRBs are really hard to see, but they’re not uncommon,” Masui said. “If your eyes could see radio flashes the way you can see camera flashes, you would see them all the time if you just looked up.”
While these bursts would be intriguing enough due to their mysterious nature, scientists also believe that they can use the bursts to better understand the universe and even map the distribution of gas throughout it.
When these radio waves travel 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 could help scientists estimate how far it has traveled and how much gas it has encountered.
“It contains a record of the structure of the universe that it passed through to get from the source to us,” Masui said. “For this reason, we believe they are going to be the ultimate tool for studying the universe.”
Many of these radio-light bursts detected by CHIME have traveled from distant galaxies and were likely created by incredibly energetic sources – but researchers are still trying to determine the exact nature of those sources.
With sufficiently rapid radio bursts, it may be possible to map the large-scale structure of the universe.
“These large structures are the threads of the cosmic web,” said Alex Josephy, doctoral student in physics at McGill University in Canada. “With the FRB Catalog, we detected this correlation between FRBs and large-scale structure. It’s really, really exciting and ushers in a new era of cosmology (rapid radio burst).”