14 | New Scientist | 29 February 2020
THE strangest fast radio burst
(FRB) yet is helping us to narrow
down the possible causes of these
powerful blasts of radio waves
from space. The unusual patterns
we see in its light suggest it may
come from a wobbly neutron star.
FRBs generally last only a few
milliseconds, but some of them
repeat. We don’t know what
causes them, although black holes,
strange quark stars and alien
spaceships have all been put
forward as explanations.
Sorting it out has been made
harder because the timing of
the repeating FRBs has seemed
random, and many potential
sources of repeating blasts should
result in predictable patterns.
In February, the Canadian
Hydrogen Intensity Mapping
Experiment (CHIME) found such a
pattern in a repeating FRB’s flashes
for the first time: the bursts arrive
in four-day windows, followed by
about 12 days without bursts and
then another window of activity.
That regularity is a clue in the
hunt for FRB sources. Several
research groups suggest that these
patterns could be caused by thewobble of a highly magnetised
neutron star called a magnetar.
Magnetars emit powerful
beams of light, which we could
detect as FRBs when they reach
Earth. However, they spin so
quickly that we would expect
to see a period of bursts every
few seconds rather than over
a period of weeks.
To find out if a magnetar could
produce what we see, Yuri Levin atColumbia University in New York
and his colleagues – and several
other groups of researchers –
suggested a wobble in its spin
(arxiv.org/abs/2002.04595).
“If you throw a body into the
air and set its initial spin around
some random direction, if the
body is not too symmetric you
will observe it tumble,” says Levin.
Magnetars aren’t perfectly
spherical, but are deformed by
their fast spins and powerful
magnetic fields, so they may rotate
with a slight wobble, like a spinning
top on an uneven surface. Thewobble could also come from
the gravitational effects of a
companion orbiting the magnetar,
suggest Huan Yang at the Perimeter
Institute in Canada and Yuan-
Chuan Zou at Huazhong University
of Science and Technology (arxiv.
org/abs/2002.02553).
Both mechanisms would
cause a magnetar’s emitted light
beam to trace a circle through
the sky. If the circle takes 16 days
to complete, the pattern would
match what CHIME observed: four
days in which we can see the beam,
and then 12 days as it circles back.
“I think all of these models
make predictions that will be
testable, if not in the next month,
within the year,” says Levin.
“This is a spectacular source,
and as long as it keeps providing
bursts and doesn’t turn off for
some reason, everything about it
will be extremely well-measured.”
If this FRB comes from a
magnetar, maybe the rest of them
do too: magnetars that turn off
and on could cause repeating FRBs
that appear not to have patterns in
their signals, as well as FRBs that
SCIENCE PHOTO LIBRARY/ALAMY don’t appear to repeat, says Yang. ❚News
“No other cave-dwelling
animal of any kind can
confidently be attributed
to the dinosaur era”Palaeontology99-million-year-old
cockroach is earliest
cave-dwellerA COCKROACH preserved in amber
is the earliest cave-dwelling animal
identified from the dinosaur era.
The specimen was found in
the Hukawng Valley in Myanmar.
The rocks where it was discovered
are 99 million years old, midway
through the Cretaceous period,
when the last dinosaurs lived.
This new Cretaceous cockroach
has been dubbed Mulleriblattina
bowangi by a team led by PeterVršanský at the Slovak Academy
of Sciences in Bratislava.
“It’s clearly a cave inhabitant,”
says Vršanský. It is pale white,
having lost its pigments, and its
eyes and wings are drastically
reduced. It has particularly long
antennae, which presumably helped
it navigate in the dark (Gondwana
Research, doi.org/dm65).
The insect is also missing leg
spines. “All cockroaches have spines
because it’s passive protection
against predators,” he says. “These
don’t have these spines, because
in caves there is no threat.”
It is strange that a cave-dwellingorganism became trapped in amber,
which comes from tree sap. It may
have wandered close to the cave
entrance and come into contact with
amber from trees growing nearby,
says Vršanský.
No other cave-dwelling animal,
of any kind, can be confidently
attributed to the dinosaur era
or earlier, he says.
Vršanský’s team reconstructed
the family tree of Nocticolidae,the cockroach family to which M.
bowangi belongs. They found that
when Nocticolidae lineages entered
caves, they began evolving rapidly.
“In a very short time, their
evolution becomes very rapid and
very strange, because bizarre and
strange forms originate,” he says.
However, the family tree suggests
these cave-dwelling lineages
tended to die out relatively quickly,
within about 30 million years. It is
unclear why, he says, but it could
have been that isolation led to
inbreeding or a lack of viruses
bringing in new genetic material. ❚
Michael MarshallAstronomyLeah CraneWobbly star may be radio burst culprit
Mysterious signals from space could come from a spinning star
Light beams from
magnetars could be
behind odd radio signals