An interferometric radio telescope at the Dominion Radio Astrophysical Observatory in Okanagan Falls, B.C., is shown in this undated handout photo.Andre Recnik/The Canadian Press
The first results from a unique Canadian radio telescope are shedding light on the mysterious cosmic phenomenon called fast radio bursts – fleeting but powerful blasts of radio energy that are produced by unknown sources far beyond our own galaxy.
Working with the Canadian Hydrogen Intensity Mapping Experiment, or CHIME, located in British Columbia’s Okanagan Valley, researchers say that in a first test of the new instrument last summer, the telescope recorded a total of 13 of the elusive bursts during just July and August. In comparison, less than 50 were found in all the previous years since scientists first became aware of the phenomenon in 2007.
CHIME’s discoveries, published Wednesday in the journal Nature and presented this week at the annual meeting of the American Astronomical Society in Seattle, provide a striking validation of the instrument’s technical capabilities. Among other things, they reveal that the bursts were received across the entire range of radio frequencies to which the telescope is sensitive. Until it switched on, there was no guarantee that CHIME would detect any at all.
“It’s very exciting,” said Victoria Kaspi, a McGill University astrophysicist and one of the leaders of the effort. “It was entirely possible that the phenomenon would not be observable at those frequencies.”
Dr. Kaspi said that she and her colleagues already know that they have many more fast radio bursts recorded in data taken from last September onward as they continue to optimize their system.
The results effectively confirm that the Canadian instrument is set to become a workhorse for spotting fast radio bursts in great numbers, a key step toward cracking the puzzle of what causes them and for using the bursts to learn about the large-scale properties of the distant universe.
“It really looks like CHIME is defining a new epoch in the science of fast radio bursts,” said Casey Law, a radio astronomer at the University of California, Berkeley who is not a member of the CHIME team.
Fast radio bursts are point sources of radio waves in the sky that typically last for just a few thousandths of a second before vanishing as abruptly as they appear. Their ability to stand out across the vast depths of intergalactic space indicates that whatever is producing them could be as much as one trillion times more energetic than the most prominent sources of radio emission within our own galaxy.
In their effort to explain what might produce such brief but brilliant outbursts, theorists have considered a variety of cosmic cataclysms, such as exploding stars and colliding black holes.
However, among the 13 new bursts detected by CHIME, one was observed on multiple occasions – only the second time that a burst has been known to repeat.
This complicates the view that the bursts are produced by one-time destructive events. An alternative explanation looks to a class of exotic objects known as magnetars – rapidly spinning and highly magnetized neutron stars that are left over after a supergiant star goes supernova. Such an object might generate repeated fast radio bursts, like a scaled-up version of the solar flares that repeatedly erupt on the sun.
“You really can’t rule out yet that they don’t all repeat,” said James Cordes, a radio astronomer at Cornell University who discovered the first repeating burst in 2012.
Astronomers had hoped that CHIME’S unusual design, which employs four large, trough-shaped antennas to map a broad swath of the radio sky, would also prove an effective tool for detecting transient phenomenon such as fast radio bursts. Now that bet appears to be paying off.
“The instruments that have big fields of view, like CHIME, are really going to sweep up a lot of these things,” Dr. Cordes said.
CHIME is not without competition, however. In recent months, astronomers using the ASKAP, a radio-telescope array based in Australia, reported 19 new fast radio bursts. The two instruments, which cover the two opposite hemispheres of the sky and also observe at different frequencies, are seen as complementary to each other.
What makes CHIME exceptional is its relatively low cost relative to conventional radio telescopes that are more commonly made up of one or more dishes that can be pointed to different sources in the sky. Instead, CHIME takes in most of the sky that passes overhead as the Earth turns, and relies on computer power to separate interesting signals from an ocean of natural and artificial sources of radio noise.
“It’s really a software telescope,” said Kendrick Smith, a cosmologist with the Perimeter Institute for Theoretical Physics in Waterloo, Ont., who helped develop the system.
Dr. Smith said that a major challenge in preparing CHIME to search for fast radio bursts was getting the software to distinguish cosmic sources that would be of genuine interest from those that are simply attributable to random radio waves reflecting off of passing aircraft, among other false positives.
Cherry Ng, a postdoctoral researcher at the University of Toronto’s Dunlap Institute who was involved in developing and testing CHIME and is now analyzing the results, said that it was momentous for the entire team to see the Canadian telescope deliver on its promise.
“It’s really satisfying to know that the work we’ve put in is being rewarded," she said. “Now we’re pretty curious to know what these [fast radio bursts] are."
THE CHIME RADIO TELESCOPE
The telescope has no moving parts but collects
radio signals in a narrow zone of sky that runs
north to south. As the Earth turns, celestial
objects that emit radio waves
pass through the zone and
are detected by CHIME.
3
Horizon
1
100
METRES
SOUTH
2
20
METRES
4
NORTH
Person for scale
Data rate: CHIME handles about one terabyte
of data each second – equivalent to all the
cellphone traffic in North America
Focal line: each line consists of 256
individual receivers spaced 30 cm apart
Reflectors: made of steel mesh parabolic
“half-pipes”aligned north-south
Field of view: nearly the entire sky that can
be seen from the telescope’s latitude rotates
through its field of view every 24 hours
Processors: on-site computer system
cross-compares inputs from 1,024 receivers
to work out incoming direction of signals
and map the radio sky overhead
1
2
3
4
CARRIE COCKBURN/THE GLOBE AND MAIL,
RESEARCH: IVAN SEMENIUK, SOURCE: CHIME COLLABORATION
THE CHIME RADIO TELESCOPE
The telescope has no moving parts but collects radio
signals in a narrow zone of sky that runs north to south.
As the Earth turns, celestial objects that emit radio waves
pass through the zone and are
detected by CHIME.
3
Horizon
1
SOUTH
100
METRES
2
20
METRES
NORTH
4
Person for scale
Data rate: CHIME handles about one terabyte of data
each second – equivalent to all the cellphone traffic
in North America
Focal line: each line consists of 256 individual
receivers spaced 30 cm apart
Reflectors: made of steel mesh parabolic
“half-pipes”aligned north-south
Field of view: nearly the entire sky that can be seen
from the telescope’s latitude rotates through its field
of view every 24 hours
Processors: on-site computer system cross-compares
inputs from 1,024 receivers to work out incoming
direction of signals and map the radio sky overhead
1
2
3
4
CARRIE COCKBURN/THE GLOBE AND MAIL,
RESEARCH: IVAN SEMENIUK, SOURCE: CHIME COLLABORATION
THE CHIME RADIO TELESCOPE
The telescope has no moving parts but collects radio signals
in a narrow zone of sky that runs north to south.
As the Earth turns, celestial objects that emit radio waves pass
through the zone and are detected by CHIME.
3
Horizon
SOUTH
1
100
METRES
4
2
NORTH
20
METRES
Person
for scale
Data rate: CHIME handles about one terabyte of data each second –
equivalent to all the cellphone traffic in North America
Focal line: each line consists of 256 individual receivers spaced 30 cm apart
Reflectors: made of steel mesh parabolic “half-pipes”aligned north-south
Field of view: nearly the entire sky that can be seen from the telescope’s
latitude rotates through its field of view every 24 hours
Processors: on-site computer system cross-compares inputs from 1,024 receivers
to work out incoming direction of signals and map the radio sky overhead
1
2
3
4
CARRIE COCKBURN/THE GLOBE AND MAIL, RESEARCH: IVAN SEMENIUK, SOURCE: CHIME COLLABORATION