For more than a decade, astronomers have been trying to solve the mystery of fast radio bursts. Know their name, and you know their story: Fast radio bursts last only a few milliseconds, they give off radio waves, and — with a couple of notable exceptions — they burst once and then they are gone. But now, scientists are about to get a bonanza of new clues as to the true nature of fast radio bursts, in part thanks to a new radio telescope in British Columbia called CHIME.
First, some history: The first fast radio burst was discovered in 2007, when astronomers unearthed it in archived data from the Parkes radio telescope in Australia. Since then, astronomers have found about 60 more, and they all seem to be coming from beyond Earth — far beyond, sometimes billions of light years away, well outside the Milky Way.
Astronomers have been able to figure out a few things about fast radio bursts based on the bursts’ distance, duration, and number. First, they are powerful, giving off as much energy in milliseconds as our Sun does in years or decades. Next, because they are so short, they must be coming from something pretty small, astrophysically speaking: about a thousandth the diameter of the Sun. That narrows the likeliest sources down to things like black holes and neutron stars. Strangest of all, when astronomers do the math, they find that there must be between 5,000 and 10,000 of them going off every day. It’s like waking up and realizing that you’re in the middle of the 4th of July fireworks, and have been, forever — but somehow didn’t realize it.
How is it possible that we didn’t notice them for so long? “You have to be looking at the right place at the right millisecond,” says Shami Chatterjee, an astrophysicist at Cornell University who studies fast radio bursts and neutron stars. And most radio telescopes only take in a tiny “pencil-beam” of the sky at any given moment, he says, leaving fast radio bursts in the vast everywhere-else to pop off unnoticed.
Which brings us to CHIME. Whatever you picture when you picture a radio telescope, it probably isn’t CHIME; if you passed CHIME on the road, you might mistake it for a solar panel array or maybe a skateboard practice facility. It catches radio waves in four smile-shaped chutes, each 200 meters long and 20 meters wide, and bounces them up to a catwalk strung with hundreds of radio antennas. The telescope takes in a huge amount of data — 13 terabytes a second — and processes it in real-time on a custom “search engine” that sits in a 40-foot shipping container on the telescope site. And unlike those tunnel-vision telescopes, CHIME can watch huge swaths of the sky all at once. If other radio telescopes are like fishing rods casting out their slender lines, CHIME is like a net strung across the ocean.
Last week, CHIME researchers announced that they had picked up 13 fast radio bursts, including an especially coveted catch — a fast radio burst that goes off again and again, making it easier to study. (It’s only the second known “repeater.”) The remarkable part is that they found these bursts during a “pre-commissioning” phase, while the telescope was still being prepped and tested for its real science run.
Working at full capacity, CHIME could turn up dozens of fast radio bursts every day. And it isn’t the only telescope rapidly racking up new finds. Telescopes like the Very Large Array and the Australian Square Kilometer Array Pathfinder, which announced 20 new bursts just last fall, are also searching. Unlike CHIME, these telescopes will likely be able to identify the bursts’ host galaxies as well as the bursts themselves.
Astronomers aren’t expecting that CHIME will deliver an immediate solution to the mystery of fast radio bursts, but they are anticipating something that, to scientists, may be even better: lots and lots of data.
Kate Becker: twitter.com/kmbecker