Australian researchers using a CSIRO radio telescope in Western Australia have nearly doubled the known number of ‘fast radio bursts’— powerful flashes of radio waves from deep space.
The team’s discoveries include the closest and brightest fast radio bursts ever detected.
Fast radio bursts come from all over the sky and last for just milliseconds.
Scientists don’t know what causes them but it must involve incredible energy—equivalent to the amount released by the Sun in 80 years.
“We’ve found 20 fast radio bursts in a year, almost doubling the number detected worldwide since they were discovered in 2007,” said lead author Dr Ryan Shannon, from Swinburne University of Technology and the OzGrav ARC Centre of Excellence.
“Using the new technology of the Australia Square Kilometer Array Pathfinder (ASKAP), we’ve also proved that fast radio bursts are coming from the other side of the Universe rather than from our own galactic neighborhood.”
Co-author Dr Jean-Pierre Macquart, from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), said bursts travel for billions of years and occasionally pass through clouds of gas.
“Each time this happens, the different wavelengths that make up a burst are slowed by different amounts,” he said.
“Eventually, the burst reaches Earth with its spread of wavelengths arriving at the telescope at slightly different times, like swimmers at a finish line.
“Timing the arrival of the different wavelengths tells us how much material the burst has traveled through on its journey.
“And because we’ve shown that fast radio bursts come from far away, we can use them to detect all the missing matter located in the space between galaxies—which is a really exciting discovery.”
CSIRO’s Dr Keith Bannister, who engineered the systems that detected the bursts, said ASKAP’s phenomenal discovery rate is down to two things.
“The telescope has a whopping field of view of 30 square degrees, 100 times larger than the full Moon,” he said.
“And, by using the telescope’s dish antennas in a radical way, with each pointing at a different part of the sky, we observed 240 square degrees all at once—about a thousand times the area of the full Moon.
“ASKAP is astoundingly good for this work.”
Dr Shannon said we now know that fast radio bursts originate from about halfway across the Universe but we still don’t know what causes them or which galaxies they come from.
The team’s next challenge is to pinpoint the locations of bursts on the sky.
“We’ll be able to localize the bursts to better than a thousandth of a degree,” Dr Shannon said.
“That’s about the width of a human hair seen ten meters away, and good enough to tie each burst to a particular galaxy.”
ASKAP is located at CSIRO’s Murchison Radio-astronomy Observatory (MRO) in Western Australia, and is a precursor for the future Square Kilometer Array (SKA) telescope.
The SKA could observe large numbers of fast radio bursts, giving astronomers a way to study the early Universe in detail.
The researchers and their institutions acknowledge the Wajarri Yamaji as the traditional owners of the MRO site.
Despite considerable efforts over the past decade, only 34 fast radio bursts—intense bursts of radio emission from beyond our Galaxy—have been reported. Attempts to understand the population as a whole have been hindered by the highly heterogeneous nature of the searches, which have been conducted with telescopes of different sensitivities, at a range of radio frequencies, and in environments corrupted by different levels of radio-frequency interference from human activity. Searches have been further complicated by uncertain burst positions and brightnesses—a consequence of the transient nature of the sources and the poor angular resolution of the detecting instruments. The discovery of repeating bursts from one source, and its subsequent localization to a dwarf galaxy at a distance of 3.7 billion light-years, confirmed that the population of fast radio bursts is located at cosmological distances. However, the nature of the emission remains elusive. Here we report a well controlled, wide-field radio survey for these bursts. We found 20, none of which repeated during follow-up observations between 185–1,097 hours after the initial detections. The sample includes both the nearest and the most energetic bursts detected so far. The survey demonstrates that there is a relationship between burst dispersion and brightness and that the high-fluence bursts are the nearby analogs of the more distant events found in higher-sensitivity, narrower-field surveys.
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