New Fast Radio Burst discovery finds ‘missing matter’ in the universe
MILWAUKEE _ An international team of scientists using a combination of radio and optical telescopes has for the first time managed to identify the location of a fast radio burst, allowing them to confirm the current cosmological model of the distribution of matter in the universe.
On April 18, 2015, a fast radio burst (FRB) was detected by the Commonwealth Scientific and Industrial Research Organisation (CSIRO)’s 64-m Parkes radio telescope in Australia. An international alert was triggered to follow it up with other telescopes and within a few hours, a number of telescopes around the world had found the signal, allowing astronomers to determine the location, and ultimately the distance, to the source.
FRBs are mysterious bright radio flashes generally lasting only a few milliseconds. Their origin is still unknown, with a long list of potential phenomena associated with them. FRBs are very difficult to detect; before this discovery only 16 had been detected in the decade since they were first seen.
“In the past FRBs have been found by sifting through data months or even years later. By that time it is too late to do follow up observations,” said Evan Keane, Project Scientist at the Square Kilometre Array Organization and the lead scientist behind the study. To remedy this, the team developed its own observing system to detect FRBs within seconds, and to immediately alert other telescopes, when there is still time to search for more evidence in the aftermath of the initial flash.
David Kaplan, an astronomer at the University of Wisconsin-Milwaukee, is a member of the team that searched through data from other telescopes and also helped interpret the data to form a more comprehensive picture of this mysterious event.
“We’ve been able to locate the object and determine its distance – several billion light-years away,” Kaplan said. “That’s important because the nature of the radio signals from FRBs indicate how much material they’ve gone through.
“Most of the gas in the universe isn’t in galaxies. Instead, it lies between them in the ‘intergalactic medium.’ Knowing the distance to this object lets us take a ‘census’ of the intergalactic medium in a way that hasn’t been possible before.”
In the current model, the universe is believed to be made of 70% dark energy, 25% dark matter and 5% “ordinary’ matter,” the matter that makes up everything we see. However, through observations of stars, galaxies and hydrogen, astronomers have only been able to account for about half of the ordinary matter, the rest could not be seen directly and so has been referred to as “missing.”
“The good news is our observations and the model match, we have found the missing matter,” Keane said. “It’s the first time a fast radio burst has been used to conduct a cosmological measurement.”
In the future, the Square Kilometre Array, with its extreme sensitivity, resolution and wide field of view is expected to be able to detect hundreds of FRBs and to pinpoint their host galaxies. A much larger sample will enable precision measurements of cosmological parameters such as the distribution of matter in the universe, and provide a refined understanding of dark energy.