FRB 1221102

The space has always been a center of attraction for physicists and astrologers. It has kept amusing humans with unique characteristics. Though they are all guided by pre-defined laws, it is not easy to predict them. It has always shown us that what we think need not be always right. Recently, one such incident took place, which rendered the scientist speechless.

BILLIONS OF YEARS ago, an unknown object sent a seriously bright burst of radio waves into space. They traveled across the universe, past galaxies and clouds of gas and who knows what else. And in 2012, the burst arrived at the Arecibo radio telescope when astronomers happened to be watching.

They kept searching that same spot in the sky. In 2015, they found 16 additional flashes. Then, in August and September 2016, nine more appeared. And this week, astronomers announced that these newest measurements helped them finally zero in on the bursts’ home: a dim dwarf galaxy three billion light-years away. Something inside this tiny galaxy was sending pulses that lasted just milliseconds but packed enormous energy, members of a still-mysterious class called “fast radio bursts.”

Learning that these particular bursts came from long ago, from some bursting object in a galaxy far, far (far) away, is an important step for this field of research. But it’s also like playing Clue and concluding that the crime was committed in the conservatory. To solve the crime, you still have to determine whether the dastardly deed was done by Mrs. Peacock with the candlestick or Colonel Mustard with the rope.

That continuing conundrum shows off the way science works, in a way we don’t usually get to see. Astronomers don’t often happen upon a total mystery. Much of their work involves looking directly at objects they know exist—stars, planets, supernovae—and studying processes and properties. Fast radio bursts, though, appeared out of nowhere, unexpected and un-asked-for, coming from question-mark objects with question-mark properties because of question-mark processes. Astronomers now have the privilege of figuring out the what, where, why, and how—from total scratch—and we have the privilege of watching the discovery process take place from its start.

To forecast what will likely happen next in the ongoing case of the super-energetic fast radio bursts, history helps. Specifically, the twentieth-century discoveries of pulsars and gamma-ray bursts, which also began with on-and-off flashes from unknown entities.

The very first on-off from a fast radio burst came in 2007, when astronomer Duncan Lorimer was sifting through archived data, searching for undiscovered pulsars. But instead, he found something that flashed just once, brighter than a pulsar and seemingly much farther away. He didn’t know what he was looking at. Neither did anyone else.

This is a familiar story arc in astronomy. It’s really the best way to find something utterly new: by accident, while searching for something known. It happened to Jocelyn Bell, who was looking for the twinkling of quasars—the super bright cores of galaxies with super massive black holes in feeding mode—when she stumbled upon a repeating radio blip. It blipped too fast to be any regular star. Was it aliens? Human technology? A planet? A mistake? It wasn’t until she found another blipper that she felt confident it was part of the natural universe at all. Then, when she and her adviser found two more, the blippers became a Thing. After they went public, people proposed more explanations, including the correct one—pulsars, the fast-spinning neutron stars left over after supernova explosions.

Artist rendition of the dishes of the Karl G. Jansky Very Large Array are seen making the first-ever precision localization of a Fast Radio Burst, and thereby pointing the way to the host galaxy of FRB121102.

Gamma-ray bursts, too, are in encyclopedias because of an accident. In the 1960s, US government satellites were hanging out, watching for the high-energy indications of Soviet nuclear tests. They picked up 16 weird bursts of gamma rays that didn’t match up with nukes’ characteristics. In 1973, the government declassified the discovery and declared that the bursts must have come from space.

But after Lorimer saw his first burst, he didn’t get more of the same from the sky, as Bell and the Soviet-watchers did. No one saw any more fast radio bursts, from anywhere in the sky, for years. People doubted the astronomical origin of the original specimen, suggesting it came from Earth—and, indeed, astronomers in Australia accidentally produced a set of similar radio bursts by opening their microwave door before cooking was complete. There wasn’t even a category for that kind of behavior.

Since then, astronomers have found 18 sources of fast radio bursts—including the only one that repeats, the one first spotted in 2012. Shami Chatterjee, the lead in this latest discovery, decided to focus efforts there. “This is a good place to go fishing because you’re more likely to see a fast radio burst at this spot,” says Chatterjee. The team began watching the area with the Very Large Array in late 2015, searching for the burster’s precise location in space.

They watched for another burst for dozens of hours, in observations in November 2015 and April and May 2016, and saw nothing. “The field of transients is special in that we need to wait for the universe to provide an event for us,” says Casey Law of the University of California, Berkeley, who led the project’s software and data-taking developments. Finally, a burst appeared, in a set of observations that began in August. Then, so did eight more. That dataset allowed the team to pinpoint where the signals came from, a position they later zoomed in on even more precisely with radio telescopes around the world. And once they got images of that same spot from an optical telescope called Gemini North, they saw a faint smudge of shine, more like something you’d try to wipe off your screen than the answer to a big astronomical question. But that smudge was actually a tiny galaxy, around 3 billion light-years distant. Somewhere inside, the astronomers knew lurked the burster.

To be continued.............