An artist's impression of a fast radio burst (FRB) arriving at Earth. The colors represent the burst arriving at different radio wavelengths, with long wavelengths (red) arriving several seconds after short wavelengths (blue). This delay is called dispersion and occurs when radio waves travel through cosmic plasma. Credit: Credit: Jingchuan Yu, Beijing Planetarium.
For more than a decade, astronomers have been puzzled about the origins of so-called fast radio bursts (FRBs), which are fleeting but energetic flashes of light in deep space. In fractions of a second, these explosions launch as much energy into space as the Sun radiates in a single day.
Nearly 800 of these enigmatic objects have been discovered flashing on and off across the sky since the first one was discovered in 2007. Most have flashed once and not repeated, while a few appear to flash thousands of times each day.
“We have no idea what is causing them,” says Ayush Pandhi of the University of Toronto in Canada. “It's one of the great mysteries of astronomy right now.”
One idea postulates that FRBs may represent powerful magnetic eruptions from long-dead stars known as magnetars. For example, an FRB with an intriguing and unexpected structure, detected in 2022, may be the result of a magnetar.”with steroids.” Many other questions remain about their nature, including where in the sky they originate and whether single and recurring explosions arise from different types of sources. Now, using observations from a telescope in British Columbia that has observed the vast majority of the mysterious explosions, called the Canadian Hydrogen Intensity Mapping Experiment (RING), Pandhi and his colleagues may have taken another step toward decoding the types of objects that produce FRBs.
Galaxies like our Milky Way, which are moderately dense, appear to produce FRBs that burst only once, while more densely populated galaxies, which also boast extreme magnetic fields, likely generate hyperactive, repeated bursts of radio energy, they report. Pandhi and his team in an article. published on June 11 in The Astrophysical Magazine.
While astronomers have yet to pin down the individual galaxies from which FRBs emerge (a key aspect to understanding the elusive bursts), the latest findings offer theorists more information about the local environments from which the flares emerge.
Decoding the mysterious origins of fast radio bursts
Unlike other radio telescopes that change their view to glimpse separate areas of the sky, CHIME is not equipped with moving parts. So, “you just look up until you see an explosion and do your best to figure out exactly where it's coming from,” Pandhi says. From CHIME's fixed view, parts of the sky appear and disappear from view every 15 minutes, allowing you to scan the entire sky for unique and recurring FRBs. The telescope easily detects three FRBs each day, Pandhi says.
Each burst carries bits of information about everything between Earth and the FRB itself, meaning the bright bursts are also encoded with clues about the intervening material that light passes through for eons on its way to Earth. providing information about galaxies and intergalactic material that would otherwise be difficult to obtain. get.
Using the CHIME data, Pandhi and his team compared the newly discovered unique FRBs to previously known hyperactive bursts. Specifically, the team studied the angle at which light from an FRB is oriented and how far it has traveled, revealing how much material it has passed through. “This is a new way of analyzing the data we have on FRBs,” Pandhi said in a recent Press release. “It allows us to reconsider what we think FRBs are and see how repeat and non-repeat FRBs may be different.”
The team found that the recurring explosions appear to come from galaxies much more gas-filled than our own. Meanwhile, single-shot FRBs appear to come from galaxies that are less dense or have weaker magnetic fields than the Milky Way. However, “they go through so much that it's hard to pinpoint exactly what's causing that churn,” Pandhi says.
Soon, Pandhi plans to use the Very Large Array in New Mexico to unravel aspects of FRB rotation influenced by the Milky Way, which may shed more light on FRB host galaxies. Astronomers can then simulate various properties observed in those host galaxies and compare them to our own. “It's a prediction game,” Pandhi says.
Other astronomers have recently come closer to finding the origins of FRBs. Earlier this year, for example, a team using the Hubble Space Telescope narrowed the location of an FRB that erupted in the middle of the universe (the most distant and powerful explosion recorded to date) to a drop-shaped galaxy cluster which existed about 5 billion years after the Big Bang. The observation also raised intriguing questions, including whether the radio burst arose from a single galaxy or a complex, interacting system of up to seven galaxies potentially in the act of merging.
With highly sensitive telescopes like CHIME and China's FAST (Five Hundred Meter Aperture Spherical Radio Telescope), astronomers are already cataloging hundreds of FRBs and may soon be closer to decoding their mysterious origins.
“We just need to keep finding more of these FRBs, both near and far, and in all these different types of environments,” Alexa Gordon of Northwestern University in Illinois, who led the Hubble study, said in a report earlier this year. . nasa statement.
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