A Canadian telescope has found more than 500 mysterious cosmic events known as “fast radio bursts” (FRB), telling us more about this poorly known phenomenon than ever before.
A team scanning 2018-19 archival data from the Canadian Hydrogen Intensity Mapping Experiment (CHIME) revealed 535 pulses of radio energy from outside the galaxy, on what could be a crucial next step in learning more about the Universe’s history.
This catalogue will also help scientists better understand the nature of FRBs, since the new survey quadruples the number of known bursts and creeps accumulated observations towards statistical validity. CHIME member Deborah Good said in an interview that a larger catalogue helps scientists narrow down the key properties to better understand these cosmic bursts.
“Imagine you’re trying to understand the properties of university students,” said Good, a PhD candidate at the University of British Columbia. “I can’t do that in a classroom full of 20 university students, but you will be able to get some things right: they’re human, they’re of all genders. But you might not know – for example – if one of them has glasses, is that because there’s only this one exceptional student with glasses in the whole university? Or are there many with glasses?”
The new survey of FRBs, for example, revealed repeating bursts with different rates of rotation — some rotating at high rates, and some rotating more slowly. It may be, for example, that a repeating burst is not necessarily associated with a high rotation rate.
“There’s a lot more ability to say that we’re really starting to understand these objects, and starting to answer questions,” Good said.
One of those questions is fundamental — determining the cause of FRBs. Because these bursts are transient and can appear just about anywhere in the sky, it’s difficult for professional telescopes to pivot to the location of a burst to find more information. (CHIME, happily, stands apart from many radio telescopes as it can survey the entire visible sky at once and catch transient events — but the drawback is it is poor at zeroing in on individual targets, Good said.)
Most scientists say that FRBs are likely associated with ultra-dense neutron stars, which are the leftovers of more massive stars that explode as supernovas. In particular, FRBs may be linked to a flavour of neutron stars that are called magnetars, so called due to the stars’ unusually high magnetic field. But more observations will be required to identify the cause, Good said.
Looking to the future, Good said more location data could come once CHIME adds some planned “outriggers” to its central observation hub in British Columbia’s Okanagan Valley, at the National Research Council’s Dominion Radio Astrophysical Observatory near Penticton. The project is in its early stages, but eventually it would situate the outriggers — or mini-observatories — thousands of kilometres away from the central hub in British Columbia.
The outriggers and the main CHIME observatory would then work together as a massive interferometer, allowing a virtual “telescope” that would greatly expand the telescope’s diameter — and by association, the sensitivity of its observations. Perhaps CHIME could then more precisely locate future FRBs to better understand the Universe’s origin story, Good said.
In cosmology, she explained, having objects with known brightness and distance often helps build on our knowledge of the cosmic neighborhood. (A commonly cited example is one type of supernova that explodes with consistent luminosity, allowing astronomers to chart vast distances in space with these “standard candles”). With FRBs, she said, “we have some potential to add those to our list of things we can observe, to better do cosmology.”
A presentation on the FRBs was made in June at the 238th meeting of the American Astronomical Society (AAS), a major gathering of scientists at which new findings like this are regularly brought to the community, sometimes while peer review is ongoing.
This biweekly column by Canadian science and space journalist Elizabeth Howell focuses on a trending news topic in Canadian astronomy and space.