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NEWS & TECHNOLOGY
Bid to explain radio its matter. Some ideas suggest interacting with AGNs to produce
the characteristic radio waves.
that dark matter, the mysterious
substance thought to make up
bursts from space 85 per cent of matter in the Close encounters
universe, could be sucked into a
A pulsar traversing an asteroid
neutron star and cause a collapse belt could strip away charged
that would spew out FRBs. particles from an asteroid’s
Chelsea Whyte of Cape Town in South Africa. surface and produce radio waves
Platts and her colleagues have Giant bubbles and pulses characteristic of an FRB. Or a
STRANGE flashes of radio waves grouped the explanations in the Rapidly rotating pulsars have comet captured by a neutron star
have been a mystery ever since following seven categories. been suggested as an FRB source could break apart and emit radio
the first one was detected in 2007. because their magnetic fields waves as it is sucked into the star.
It is tough to say what is causing Smash-ups could accelerate clumps of
these fast radio bursts (FRBs) Mergers between two large particles that can then give off Axion interactions
because most are here and gone astronomical objects could cause radio waves. Or a pulsar in a cloud One candidate for dark matter is
in a moment – only one has ever radio waves. For instance, when of dust could create a wind bubble a hypothetical subatomic particle
been seen to repeat – which makes the magnetic field of a super- as it spins, triggering an FRB called the axion. Groups of these
it tricky to gather much data dense neutron star meets that of that travels through the nebula could clump up and collapse or
about any of them. a white dwarf star – or a supernova it sits inside. Neutron stars with collide with a highly magnetised
But astronomers do have ideas ejecting its mass, or even a black extremely powerful magnetic object such as a black hole or
about where they might come hole – the fields might create fields, known as magnetars, could neutron star. The resulting
from, ranging from the mundane streams of particles that result produce a similar bubble. interactions could produce FRBs.
to the exotic, such as alien craft in radio waves. The same thing
powered by beams of light. could occur if two neutron stars Active galactic nuclei Weird stuff
A project now aims to gather collided, or a black hole collided When an enormous black hole Maybe FRBs are created in
all the most likely explanations with another black hole. sits at the centre of a galaxy exploding white holes, mirror
and whittle them down gobbling up gas and dust, some opposites to black holes that spew
(arxiv. org/abs/1810.05836). Collapses of the matter can gain speed matter instead of sucking it in. Or
“When we started the As large celestial objects collapse, due to the extreme physical maybe they come from lightning
catalogue at the beginning of the radiation can escape in the form conditions and shoot out as a jet produced on the surface of a
year, we had more theories than of radio waves. An FRB could be a before it is swallowed. These jets pulsar. String theorists suggest
we had observations, but we now result of a neutron star collapsing shine brightly under the forces FRBs could occur when the cosmic
have more observations,” says into a black hole or a quark star: of heat and friction, shooting out strings they suppose make up our
Emma Platts at the University a hypothetical star at such high from an active galactic nucleus universe oscillate or collide.
pressure and temperature that its (AGN). Some ideas about the
Might colliding neutron stars be subatomic quarks are stripped origins of FRBs suggest that “Some of these theories are
the cause of fast radio bursts?– from the neutrons that make up objects or particles may be more likely than others,” says
Shriharsh Tendulkar at McGill
University in Canada, who works
on the project. “That’s why we
set up a discussion board, so
scientists can discuss the pros
and cons of all the theories.”
For any of these ideas to be
correct, it has to account for several
oddities among the 60 or so FRBs
found so far.
The recorded signals are all
high in frequency, suggesting
they come from something
NASA’S GODDARD SPACE FLIGHT CENTER/CI LAB polarised light, while others
compact. But they have little else
in common. Some FRBs emit
don’t, for instance. What’s more,
we have only been able to pin
down a few FRBs to their home
galaxy, so we aren’t even sure if
FRBs more often than others. ■
8 | NewScientist | 27 October 2018 certain environments produce
