Canadian scientists trace 2nd strange radio signal to nearby galaxy
Found in different galaxy than 1st signal, astronomers 1 step closer to finding out where these bursts thrive
They travel through space, and they've puzzled astronomers since they were first discovered just over decade ago. They're called fast radio bursts, and thanks to a team of Canadian scientists, a new signal has been precisely located in a nearby galaxy. It's a major step to figuring out where these enigmas come from in our universe.
The findings are in part due to the Canadian Hydrogen Intensity Mapping Experiment (CHIME) Fast Radio Burst collaboration, a team made up of more than 50 scientists across North America. The team collects data from a radio telescope stationed at the Dominion Radio Astrophysical Observatory south of Penticton, B.C.
FRBs are bright bursts of radio waves that come from far beyond Earth's galaxy. Lasting less than a second, the phenomenon was first reported in 2007. Many have been spotted since, but only around a dozen have been shown to repeat — a quality crucial to spotting them again so researchers can find out more.
There are many theories of what they could be, but with such a small sample size, astronomers can't rule much out just yet. They've only traced the origins of two repeating signals so far.
"They're telling us something about an energetic arena we've had very little insight of to date," said Paul Delaney, a professor in the physics and astronomy department at York University who was not involved in the study.
"It's going to give us a window into new astrophysics, and that gives us a better understanding of the universe as a whole," he said.
The team, co-led by the universities of British Columbia, Toronto and McGill, along with the National Research Council of Canada, has been working toward that goal since 2017.
The telescope's ability to look at large portions of the sky at a time gives the team a better look at the random and elusive behaviour of FRBs, said the University of Toronto's Mubdi Rahman, CHIME research associate and co-author of the study.
"Unlike most other telescopes, CHIME stays stable and doesn't point at things. It lets the sky move," he said.
After co-ordination with CHIME, the latest burst to be tracked, known as FRB 180916.j0158+65, was spotted and tracked by the European VLBI Network, eight telescopes spanning the globe.
The eight-metre Gemini North telescope in Hawaii was the crucial last piece to trace the FRB to a spiral galaxy 500 million light years away, according to results published in the Jan. 9 edition of Nature.
Since the discovery, scientists have found nine more repeating signals from space, according to a report released earlier this week. That means they could be localized, too, identifying the environments in space they come from, what causes them — and eventually, what these massive energy bursts are.
But CHIME can't localize FRBs on its own. After seeing the signals repeat, it can narrow down the origins to certain parts of the sky. CHIME can then team up with more precise telescopes to match it with a galaxy. It's set to get an extension in a few years that will enable it to localize data points on its own.
Right now, the telescope is predicted to detect between two and 50 FRBs per day, an event rate scientists consider very high. That's putting CHIME, a Canadian led and funded project, at the forefront of FRB research.
CHIME was also behind the first repeater ever spotted, FRB 121102. It was traced to a different environment, a dwarf galaxy in 2017.
Both repeaters tracked so far have been found to originate from star-forming galaxies, an attribute that might be important for further research, said Deborah Good, a post-doctoral student at UBC and CHIME researcher.
"It's hard to say. We always have to be really careful about generalizing from a really small number like this," she said. "But it also means that every data point we get is super important."
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An Unusual Radio Telescope Could Hold The Key To Understanding Fast Radio Bursts
Imagine you are looking up into the night sky, when you see a bright flash. It only lasts for a fraction of a second. Now imagine trying to figure out what it was. This is the challenge astronomers face when trying to study fast radio bursts (FRBs).
An FRB is a radio flash that only lasts for a few milliseconds. They seem to originate from other galaxies, which means they must be extremely powerful at the source. But we don't know what they are. Ideas range from powerful events around neutron stars or black holes to signals from advanced aliens.
It's the short duration of FRBs that makes them so difficult to study. We can't predict when one might occur, and most radio telescopes will only observe one if they happen to be pointing in the right direction when one goes off. What we need is a way to look for them across wide patches of sky. It would take a different kind of radio telescope.
Fortunately, there is such a telescope. Known as the Canadian Hydrogen Intensity Mapping Experiment, or CHIME, it consists of four long parabolic reflectors than the more common dish telescope. Since it isn't focused on a small area of the sky, CHIME can capture FRBs when they happen.
One of the main goals of CHIME is to observe the distribution of hydrogen in the universe as a way to study dark energy. Atomic hydrogen is the most abundant element in the cosmos, and it emits a distinct radio signal known as the 21-centimeter line. By mapping hydrogen across the universe, CHIME can tell us how the universe expands. This is why CHIME is built to capture a wide portion of the sky.
During the summer of 2018, CHIME made three weeks of observations as part of a testing phase. During that time it observed 13 FRBs. That compares to the roughly 60 FRBs previously observed by other telescopes. One of the events CHIME observed is a repeating CHIME. These are rare but could provide the most important clues about these mysterious events.
It is estimated that when CHIME is fully operational, it could observe between two to fifty FRBs a day. It would be a wealth of data that could transform our understanding of them.
Reference: Amiri, M., Bandura, K., Bhardwaj, M. et al. "A second source of repeating fast radio bursts." Nature 566, 235–238 (2019)
I'm an astrophysicist, professor and author. You can find most of my work at briankoberlein.com
