Fast radio burst hints at its source
Scientists have detected a burst of radio waves from six billion light years away, one of a handful they’ve discovered in the past decade — and this time they have clues about its source.
Canadian Institute for Advanced Research (CIFAR) Global Scholar Alumnus Kiyoshi Masui (University of British Columbia) is the lead author on a Dec. 2 paper in the journal Nature that details the remarkable findings. A team of scientists including Masui and CIFAR Senior Fellow Ue-Li Pen (University of Toronto) and Jonathan Sievers (University of KwaZulu-Natal) analyzed 700 hours of archival data from the National Science Foundation’s (NSF) Green Bank Telescope (GBT).
They discovered the burst and found the region of space it came from was highly magnetized, suggesting it could be related to either a recently exploded star — a supernova — or else the gas-clouded inside of a nebula forming new stars. Another possibility is that it came from the dense inner regions of its host galaxy.
The finding advances our limited knowledge about fast radio bursts (FRBs), which last only a split second but carry more energy than our Sun emits over a few months. Scientists have puzzled over them since they were discovered 10 years ago.
“Astronomers in particular, we love a mystery,” says Masui. “That’s the compelling thing about these. You have these phenomena that are very energetic, appear to be coming from half way across the Universe, and we just have no idea what they are.”
After previous studies and detections from different telescopes ruled out equipment errors and noise, scientists are looking more deeply at cosmic explanations. There are many diverse theoretical models proposing explanations for fast radio bursts, including one that suggests neutron stars spinning extra fast could send out FRBs as they slow down and collapse into black holes. Other theories point to superconducting cosmic strings or evaporating black holes. The new evidence could help scientists home in on the most plausible theories.
“We’re starting to uncover clues about the environment of the sources,” Masui says.
The idea for how to search for fast radio bursts in the archival dataset originated at a 2014 CIFAR meeting in Quebec City. Discussions with CIFAR Global Scholar Alumnus Keith Vanderlinde about using algorithms to search data for fast radio burst signals brought Sievers, Masui and Pen together to write the program that found the new FRB.
Masui says collaborations in CIFAR’s Cosmology & Gravity program between scientists in two sub-fields of astronomy, pulsar astronomy and cosmology, have been important in the search for fast radio bursts. The signal from FRBs is similar to that from pulsars, and so the algorithms and methods used by pulsar astronomers have been helpful to cosmologists such as Masui.
Another upcoming project, the Canadian Hydrogen Intensity Mapping Experiment (CHIME), also benefits from this collaboration.
“The search for fast radio bursts at CHIME is a partnership between many of the CIFAR pulsar astronomers and the cosmologists,” Masui says.
The CHIME experiment is under construction in Penticton, British Columbia, under the lead of CIFAR Senior Fellow Mark Halpern and with several CIFAR researchers on the team. It will be Canada’s largest radio telescope. Masui says it has the potential to detect thousands of fast radio bursts. CHIME’s overall goal is to make a three-dimensional map of cosmic structure to investigate the expansion of the Universe.
Uncovering the origin of fast radio bursts could help scientists answer fundamental questions about the Universe. For example, we can’t detect all of the normal matter that current models predict should be in the Universe, and studying the dispersion of radio signals that have crossed galaxies could be one way to help find it. And if they do originate with black holes, FRBs could be used to learn about the fundamentals of gravity in extreme conditions.
Image: Artist impression of a Fast Radio Burst (FRB) reaching 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: Jingchuan Yu, Beijing Planetarium