Tag Archives: FRB

Fast radio burst located for the first time

Astronomers have for the first time pinpointed the location of a non-repeating fast radio burst.

In a historic first, an international team of researchers have discovered the source of a non-repeating fast radio burst and traced its origin to a galaxy 4 billion light-years away.

The monumental findings, published in AAAS journal Science on Thursday, detail the discovery and localization of FRB 180924, a powerful, one-off fast radio burst that lasted for just a fraction of a second. Speculation about the cause of the bizarre signals takes in everything from explosive neutron stars to alien spacecraft, and while we’re still not sure what’s causing them, the revelation puts astronomers one step closer to their true nature.

“This is the big breakthrough that the field has been waiting for since astronomers discovered fast radio bursts in 2007,” said Keith Bannister, lead author of the paper and principal research engineer with Australia’s Commonwealth Scientific and Industrial Research Organisation.

Knowing the distance for the burst makes it possible to calculate how powerful it was, which helps theorists come up with an explanation for what might have caused it. Similarly, knowing its location–on the outskirts of a spiral galaxy like the Milky Way–helps them further constrain those theories.

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Fast radio bursts not detected at certain radio wavelengths

In observations by two different radio telescopes operating at different radio wavelengths but looking at the same part of the sky, astronomers have found that an observed fast radio burst was not detected by one of those telescopes.

The Curtin University-led Murchison Widefield Array (MWA) and CSIRO’s Australian SKA Pathfinder (ASKAP) telescopes were searching the sky for fast radio bursts, which are exceptionally bright flashes of energy coming from deep space. These extreme events last for only a millisecond but are so bright that many astronomers initially dismissed the first recorded fast radio burst as an observational error.

In research published in the Astrophysical Journal Letters, astronomers describe how ASKAP detected several extremely bright fast radio bursts, but the MWA—which scans the sky at lower frequencies—did not see anything, even though it was pointed at the same area of sky at the same time.

Lead author Dr Marcin Sokolowski, from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), said the fact that the fast radio bursts were not observed at lower frequencies was highly significant. “When ASKAP sees these extremely bright events and the MWA doesn’t, that tells us something really unexpected is going on; either fast radio burst sources don’t emit at low frequencies, or the signals are blocked on their way to Earth,” Dr Sokolowski said.

If blocked at these lower frequencies, this tells theorists something about the environment where the burst occurred. If instead the burst does not emit in those lower frequencies, it tells them something about the burst itself.

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Scientists puzzle over possible connection between a fast radio burst and a gamma ray burst

The uncertainty of science: In trying to explain the relatively new mystery of fast radio bursts (FRB), of which only about 20 have been detected and of which very little is known, scientists are intrigued by a gamma ray burst (GRB) that apparently occurred at the same time and place of one FRB.

Seeing the FRB event in a different wavelength would normally help astronomers better understand the FRB The problem is that this particular GRB only makes the mystery of FRBs more baffling.

One puzzle is that the two signals portray different pictures of the underlying source, which seems to be as much as 10 billion light years (3.2 gigaparsecs) away. Whereas the radio burst lasted just a few milliseconds, the γ-ray signal lasted between two and six minutes, and it released much more energy in total than the radio burst. “We’ve pumped up the energy budget more than a billion times,” says study co-author Derek Fox, an astrophysicist at Penn State.

This has big implications for the FRB’s origin. One leading theory suggests that FRBs are flares from distant magnetars — neutron stars with enormous magnetic fields that could generate short, energetic blasts of energy, and do so repeatedly, as at least one FRB is known to do. Although magnetars are thought to produce γ-rays, they would not emit such high energy and over such a long time, says Fox. “This is a severe challenge for magnetar models,” he says.

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