Located in the Okanagan Valley outside of Penticton, British Columbia, there is a massive radio observatory dedicated to observing cosmic radio phenomena. It’s called the Canadian Hydrogen Intensity Mapping Experiment (CHIME), a cylindrical parabolic radio telescope that looks like what snowboarders would call a “half-pipe.” This array is part of the Dominion Radio Astrophysical Observatory (DRAO), overseen by the National Research Council (NRC).
Originally, the observatory was meant to detect radio waves from neutral hydrogen gas in the early Universe. Today, it is used for other objectives, such as detecting and studying Fast Radio Bursts (FRBs). Since it became operational, CHIME scientists have been busy sorting through terabytes of data to pinpoint signals, often finding several in a single day. To assist with all this data-mining and coordinate CHIMEs efforts with other facilities worldwide, scientists from McGill University have developed a new system for sharing the enormous amount of data CHIME generates.
The first FRB, the famous Lorimer Burst, was detected in 2007 by West Virginia University astronomer Duncan Lorimer and his colleagues using the Parkes Radio Telescope. Since then, these transient radio pulses that often last mere milliseconds have been a source of mystery and intrigue to astronomers. Before CHIME became operational in 2018, astronomers had detected only a few dozen FRBs. Since then, CHIME has been responsible for detecting over 1000 signals!
Despite this growing catalog of events, there is still much debate about what causes them. Part of what makes CHIME effective is that it relies on no moving parts and instead relies on the Earth’s rotation to monitor broad swaths of the Northern sky every day. Combined with its huge field of view and range of frequency coverage, CHIME is an almost ideal instrument for finding and studying FRBs. But being so well-suited to the study of FRBs entails a lot of responsibility and hard work.
CHIME’s daily observations can yield up to a terabyte of raw data a day, requiring a small army of researchers and lots of computing power to analyze it for potential signals. Moreover, since most FRBs only last a few milliseconds and do not repeat, it’s very challenging for other observatories to train their instruments on the source before it disappears. But with the new data-sharing system in place, key details about each FRB can be sent to observatories worldwide in real-time.
This system is known as the CHIME/FRB VOEvent Service, which was developed by scientists from McGill University (Montreal, Quebec). The system relies on the standardized language Virtual Observatory Event (VOEvent) used since 2006 to report transient astronomical events like supernovae, gravitational microlensing, and gamma-ray bursts (GRBs). Andrew Zwaniga, a research assistant in the Department of Physics at McGill, was the lead developer of the data-sharing service.
As he said in a McGill Newsroom press release, the CHIME/FRB service will allow astronomers to train their instruments on FRBs sources and gather further clues that will help unravel the mystery of FRBs. “The enormous volume of data that CHIME/FRB generates and the large number of new FRBs that it detects each day is like a gold mine for a community that is eager to point every kind of telescope that exists at the next FRB,” he said.
The system is in keeping with one of the greatest assets astronomers have today: vastly-improved information sharing between facilities worldwide. It also represents a key step towards mobilizing the resources of the international research community so the data generated by the CHIME/FRB project can be fully-exploited. It’s also consistent with the CHIME/FRB project team’s goal of making every CHIMA data accessible to the public so other observatories can conduct follow-up studies with minimal delays.
Emily Petroff, a postdoctoral researcher in the Department of Physics at McGill, played a key role in refining the alert system ahead of its public release. As she summarized, the help of the international community will advance the science of CHIME considerably. “Since CHIME/FRB began operating in 2018, it has been like drinking from a fire hose in terms of the amount of data coming through,” she said. “We simply cannot extract all the science from this; we need the world’s help.”
The CHIME/FRB VOEvent Service developers emphasize that anyone with access to a telescope that can point to locations in the Northern will be able to make use of the alerts to make follow-up observations of the FRBs detected by CHIME as well. “We have prepared tutorials and substantial documentation for new and veteran users of VOEvents to get started quickly,” said Zwaniga. “We are inviting comments and questions regarding VOEvents from the community on our public-facing CHIME/FRB community GitHub page.”
Further Reading: McGill, CHIME FRB Open Data