The fast radio bursts detected by a Canadian telescope may have been caused by colliding black holes, an astronomer at SETI Institute said.

The repeating pulses were discovered last summer by the Canadian Hydrogen Intensity Mapping Experiment (CHIME). Its findings, presented to the scientific community Jan. 9, have drawn widespread attention.

But black holes don't necessarily explain the series of bursts originating in a galaxy 1.5 billion light years away, said Seth Shostak, senior astronomer for the SETI Institute at Hat Creek Radio Observatory, about 70 miles east of Redding.

Fast radio bursts (FRBs) are pulses of radio waves a fraction of a second long.

“Some of these are only about a thousandth of a second," Shostak said.

Radio telescopes record these signals, and computers alert astronomers when there’s an anomaly.

“We’re monitoring 70 million radio signals at once,” Shostak said. “It’s all done digitally.”

The longest of these recorded pulses is one-tenth of a second long, about equal to an eye blink, he said. "If you were listening to these things, what you’d hear is a very fast slide whistle. It's a radio burst. It’s a little bit of static that starts at the high end of the radio dial and comes down in frequency."

The first single burst was recorded in 2001, but it wasn’t recognized as such by astronomers until 2007. Since then more than 60 bursts were digitally recorded, Shostak said.

Astronomers don't yet know what causes the fast radio bursts, primarily because the frequency at which they show up makes research difficult.

"Almost all of these have only been measured once," Shostak said. "You see this happen — 'beep!' — and then you don't hear it again. You can sit there and look at it (recoded data) for weeks, and you never 'hear' it again. That makes it problematic because whenever in science you only measure something once, it's pretty hard to figure out what it is you're dealing with."

One possible, but highly improbable, explanation made public interest in fast radio bursts go sky-high: Intelligent life in another galaxy.

"Some people have suggested that you shouldn't rule out the possibility that this is some kind of alien signal, that maybe it's the Klingons trying to get in touch, or maybe it's a navigation beacon for them, or something like that," Shostak said. "You can cook up some scenarios in which it might be possible."

Klingons are the outer space villains in the television series "Star Trek."

But Shostak said that's unlikely because most individual fast radio bursts come from points billions of light years apart.

“You see a fast radio burst over there in the sky, and then you find another fast radio burst over here in the sky, and these places are billions of light years apart." If aliens are sending messages, "how is it they've all been organized to produce these fast radio bursts? It takes billions of years to send a message from one galaxy to another.”

Whatever makes fast radio bursts has to be incredibly powerful to create a signal an antenna on Earth can pick up, Shostak said. “It’s likely it’s a natural phenomenon. It could be colliding black holes."

Nonetheless, he said black holes colliding doesn't necessarily explain two series of repeating bursts recorded in 2012 and 2018.

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In 2012, the Arecibo Observatory in Puerto Rico heard the first repeating bursts from what Shostak called a "rather nondescript galaxy" three billion light years away.

"The big discovery of last week was a second repeating one," Shostak said.

CHIME at Dominion Radio Astrophysical Observatory recorded the second series, 13 bursts in a three-week period in July and August, 2018.

“Once you have something that repeats, you can study it," Shostak said.

Astronomers spoke of the discovery at the American Astronomical Society's annual meeting last week in Seattle. They're hopeful about modifying existing radio telescopes to listen for more bursts.

These include the Allen Telescope Array operated by the SETI Institute at Hat Creek Radio Observatory in the area of Lassen National Forest.

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Shostak said he hopes the Allen Telescope Array will be capable of recording fast radio bursts by summer, but "it's always a money issue for our work because we're not funded by the government. It's all donations."

Depending in part on how soon SETI and other organizations can fund the adjustment of radio telescopes to detect them, Shostak said he thinks astronomers will know more about the cause of the bursts in the next two years. Whatever they are — alien messages, black-holes colliding or something else, he said it's sure to be big.

“Whatever is making this radio burst is an incredible event,” he said. “The amount of energy in that little chirp is 10 million times the energy the sun puts out in the same amount of time. It’s far away, it’s powerful and it’s mysterious."

Go to the SETI Institute for more information on the search for extraterrestrial life.