James Minchall
Peter Timbie, a UW-Madison physics professor, isn’t quite sure what he’s stumbled upon. He only knows it comes from very far away.
“Not only is it extraterrestrial,” says Timbie. “But we’re sure it’s extragalactic as well.”
He’s not talking about flying saucers or aliens — probably. Timbie and a team of researchers recently produced the first detailed portrait of a “fast radio burst” — an explosive transmission of radio waves from as far away in the universe as you imagine, caused by — well, your guess is as good as anyone’s.
“Nobody really knows what they are, and that’s what makes them so interesting,” says Timbie. “They seem to come from all different directions in the sky.”
Discovered only in 2001, fast radio bursts, or FRBs, are cryptic, baffling and, it was thought, rare. Only 15 such events had been conclusively detected before the recent work of Timbie and his team, particularly graduate student Chris Anderson. They suggest that fast radio bursts, while still mysterious, are actually common. You just need to know how to look.
Visible light is part of the electromagnetic spectrum. So are microwaves, radio waves, infrared and so on. “One of the things that’s most interesting to me is that if we could see with ‘radio eyes,’ and looked at the full sky all the time, each day there would be several thousand [bursts]. And these are pretty bright things,” he says.
Bright is a radio-eyes understatement. Each burst, lasting only a fraction of a second, equals several months’ output of our sun. “It’s a lot of energy, but it’s somewhere else,” says Timbie. “It’s so far away that the amount we collect with radio telescopes is tiny.”
As is sometimes the case in science, the recent breakthrough happened by accident. “What we set out to do was very different,” he says.
Timbie and Anderson were attempting to sketch the structure of the universe by three-dimensionally mapping the distribution of hydrogen atoms in space. That work continues, using the National Radio Astronomy Observatory in Virginia. It has the world’s largest steerable radio telescope: a massive antenna whose dish measures more than 36,000 square feet — the size of almost seven NFL football fields, 60% taller than the Statue of Liberty. It’s the largest movable land object in the world.
“It’s just a really cool instrument and a very interesting part of the country,” says Timbie. West Virginia’s Green Bank area is strange all by itself. For 20 miles around the observatory, taking in parts or all of 19 counties, there are no microwave ovens or Wi-Fi, and no radio except for police, fire and Citizens Band, or CB. This is the U.S. National Radio Quiet Zone.
These remarkable measures are necessary to screen out interference, to detect the faintest of the faint.
These are radio signals that come from — yes — a long time ago in a galaxy far, far away, reaching us only now, and nearly impossible to separate from static.
While collecting their mapping data four years ago, Timbie and Anderson inadvertently captured FRB 110523, six billion light years away. New data analysis software has highlighted the signal. “It stands out in ways that make you sure that it’s not something mundane like radio interference or cell phones or something,” says Timbie.
“Now we will try set up the analysis software so we can decide in real time if we’ve seen such an event,” he says. “And then we can alert other telescopes around the globe that we’ve seen something, and so then there’s the possibility that someone could follow up.”
Until then, much remains a mystery. FRB 110523 appears to have come from an environment where there’s a lot of matter, but what — or who — created the signal?
Timbie is at a loss to explain.
“There’s so little information in [the data],” says Timbie. “It’s really hard to imagine.”
