We don’t know where they’re coming from or when they’ll occur. All we know is these blazingly bright bursts of low-frequency radiation that emit more energy than the sun does in decades come from “some special place” in the cosmos.
So it was big news a year ago, when scientists found a repeating radio bursts from FRB 121102 (it’s been observed to flash more than 150 times) and tracked it to a dwarf galaxy 3 billion light-years from Earth. There have been roughly 30 fast radio bursters (FRBs) detected so far, but FRB 121102 is the only one that has erupted more than once.
Three-billion light years is not a trivial distance, even by the generous standards of astronomy, says SETI. “The first quasar, discovered in 1963, astounded scientists because of its truly enormous remove. But FRB 121102 is half again as far. When it burped into space, the most advanced form of life on Earth was sea scum.
“But FRB 121102 is more than merely far, far away and long, long ago. It’s more powerful than nearly anything you can name. Indeed, if you assume that energy from the burst is radiated in all directions, then in an eyeblink this object let loose about as much energy as the Sun pumps out in a year. Or if that doesn’t impress you, it’s enough energy to run humanity (at its present, prodigious burn rate) for ten trillion years.”
Harvard astronomer Avi Loeb says “we still have no new clue on whether the origin is artificial or natural.” Loeb has examined the possibility that fast radio bursts come from planet-sized radio transmitters constructed by an advanced alien civilization — perhaps evidence of powerful energy beams used to propel alien starships. He also theorized that repeater sources such as FRB 121102 are more likely to be such alien signals because natural origin explanations would most likely produce only a single burst.
Loeb and his co-author Manasvi Lingam examined the feasibility of creating a radio transmitter strong enough for it to be detectable across such immense distances. They found that, if the transmitter were solar powered, the sunlight falling on an area of a planet twice the size of the Earth would be enough to generate the needed energy. Such a vast construction project is well beyond our technology, but within the realm of possibility according to the laws of physics.
Despite the explanation proposed by Loeb and colleagues while possible, most astronomers – including those involved with recent observations says SETI.org “elevate their eyebrows at that suggestion. After all, what could motivate a society to produce signals that are so intense they can be seen from other galaxies? That would be like the sinking Titanic using a flare gun bright enough to be seen from Mars. But of greater weight is the fact that, based on the several dozen FRBs detected so far, it’s estimated that ten thousand such blasts occur throughout the cosmos every day. The incredibly widespread nature of this phenomenon strongly suggests that Nature, not intelligence, is the cause of these cosmic flashguns.”
New observations by Jason Hessels of the University of Amsterdam and a multinational crew of radio astronomers debunk alien technology as the explanation for at least one source of a burst, reported Nature. To establish where FRBs come from, Hessels and his colleagues analyzed a succession of bursts from a source called FRB 121102. The team relied on data from the Arecibo Observatory in Puerto Rico and the Green Bank Observatory in West Virginia. The bursts lasted as little as 30 microseconds each, a duration that points to a neutron star — the collapsed core of a massive star — as their origin.
Other properties of FRB 121102’s burst show that the source is embedded in a strong magnetic field, suggesting that the bursts come from a neutron star that is either near a massive black hole or inside a highly magnetized supernova remnant.
Early 2019, a group of astronomers from several Canadian universities have announced the discovery of a second radio repeater. The repeating bursts appeared last summer almost as soon as the team turned on and began tuning up a new telescope, the Canadian Hydrogen Intensity Mapping Experiment, or Chime, in British Columbia. The team announced the discovery in a pair of papers in Nature, and in a news conference at the American Astronomical Society meeting in Seattle on Jan. 9.
Chime ‘sees’ in a fundamentally different way from other telescopes, acting as a time machine allowing scientists to create a three-dimensional map of the universe extending deep into space and time. Seven quadrillion computer operations occur every second on Chime. This rate is equivalent to every person on Earth performing one million multiplication problems every second.
“Chime’s unique design will enable us to tackle one of the most puzzling new areas of astrophysics today – Fast Radio Bursts,” said Victoria Kaspi, at McGill University.”The origin of these bizarre extragalactic events is presently a mystery, with only two dozen reported since their discovery a decade ago. Chime is likely to detect many of these objects every day, providing a massive treasure trove of data that will put Canada at the forefront of this research.
The astronomers estimated that the new repeater is about 1.5 billion light-years away, roughly half the distance to the other repeater. The existence of a second repeater suggests that there are many more to be found, said Ingrid Stairs, an astrophysicist at the University of British Columbia, in a news release.
Beyond those details, writes Dennis Overbye in the New York Times, “astronomers have nary a clue. The data suggest that the radio waves from the bursts were scattered by whatever surrounds the sources. Perhaps the bursts originated in some dense clump of matter or gas, such as the remains of an exploded star. Or maybe they arose near the black holes at the hearts of distant galaxies, said Cherry Ng of the University of Toronto, who added that the burst had to have come from “some special place.”
We should thank our lucky stars, adds Overbye, that we do not live in such a “special place” in our own galaxy.
Image credit: Andrew Seymour/NAIC/ARECIBO