Image above: The Arecibo observatory in Puerto Rico. Photo courtesy of the NAIC – Arecibo Observatory, a facility of the NSF
Researchers have once again detected a burst of radio waves that have no clear origin but seem to have travelled across galaxies before arriving at our planet.
Collaborators on the Arecibo Observatory in Puerto Rico discovered the signal, called a fast radio burst, which arrived Nov. 2, 2012 and lasted only a few milliseconds before disappearing again.
Only a handful of other fast radio bursts have been detected previously, all of them by the Parkes radio telescope in Australia, with the first one reported in 2007. This is the first time that a different telescope has detected these same signals, bolstering evidence that they are not the result of equipment errors, but could be real and cosmic in origin.
“They are certainly pointing to some new and so-far unexplained phenomenon, which is always an exciting thing,” says CIFAR Senior Fellow Ingrid Stairs (University of British Columbia).
Stairs is a co-author on the paper that details the discovery, along with CIFAR Senior Fellow Victoria Kaspi (McGill University) and Global Scholar Alumnus Slavko Bogdanov (Columbia University) of the program in Cosmology & Gravity. The Astrophysical Journal published the paper July 10, 2014.
As waves travel galactic distances through clouds of cosmic particles they disperse, so that high frequency waves arrive first, followed by low frequency waves. Measuring this dispersion gives researchers an idea of how far the signal has traveled.
“The amount of dispersion we see in this burst is three times larger than the maximum amount of dispersion we expect from our own galaxy in that direction, so we believe the burst is extragalactic in origin,” Stairs says. The researchers estimate that the signals come from about 3 billion light years away. The entire Milky Way measures about 100,000 light years in diameter.
Stairs says that theories about where the bursts come from abound. Some point to the source as evaporating black holes, certain kinds of imploding neutron stars or cosmic strings working as superconductors.
“In other words, we just don’t really know at this point!” Stairs says.
Nonetheless, the Arecibo result adds another chapter to a tale of scientific mystery that began with the first detected burst reported in 2007, and five more in 2013.
Studying the radio bursts could help scientists resolve the longstanding problem of the missing matter in our universe. We can’t see all of the normal matter predicted to exist by current models, but studying the dispersion of radio signals that have crossed galaxies could help us find it.
“The “missing” matter may be between galaxies,” Stairs says.
The science of fast radio bursts may get a boost from a connection with another project involving CIFAR fellows. The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is building Canada’s largest radio telescope in Penticton, British Columbia, under the lead of CIFAR Senior Fellow Mark Halpern and with the collaboration of CIFAR Senior Fellows Gary Hinshaw, J. Richard Bond, Matt Dobbs and Ue-Li Pen, as well as Global Scholar Alumnus Keith Vanderlinde and frequent CIFAR Cosmology & Gravity guest Kris Sigurdson. CHIME’s goal is to make a three-dimensional map of cosmic structure to investigate the expansion of the Universe.
The two groups of researchers are joining forces to propose adding a second data-processing instrument to CHIME, enabling it to detect tens of the fast radio bursts per day and help identify their origin.
This research was funded in part by the Natural Sciences and Engineering Research Council, the Centre de Recherche Astrophysique de Quebec, the Canada Foundation for Innovation and CANARIE.