22 June 2019 | New Scientist | 7Black hole mysteries
newscientistlive.com/
first-black-holeTHE Milky Way’s supermassive
black hole is eerily quiet, rarely
devouring anything. Now it seems
that magnetic fields in the centre
of our galaxy could be responsible,
by steering gas and dust into orbit
around the black hole rather than
allowing them to drop in.
Darren Dowell at NASA’s Jet
Propulsion Laboratory and
his colleagues used a camera
aboard the agency’s Stratospheric
Observatory for Infrared
Astronomy (SOFIA), which is
a telescope on a high-flying
airplane, to look at the infrared
light from the centre of the galaxy.
This sort of light is completely
blocked by Earth’s atmosphere,
so the only way to observe it is
to fly high above the ground or
to use a space telescope.
The infrared light the team
observed was emitted by grains
of magnetic dust floating amid
the dust in the central 16 light
years of the galaxy. The grains
align with their long axes
perpendicular to the direction
of the magnetic field, which leaves
an observable signature in the
light they emit as they spin.
Those signatures show that
the grains are arranged in a sort
of spiral pattern similar to that
of the Milky Way itself. “For
many years, we have studied the
high-resolution structure of the
gas in this region – the mini spiral
of the galactic centre – but we
haven’t had the ability to probe
the magnetic field on such fine
scales,” says Cornelia Lang at the
University of Iowa.
The strongest force in this
location is the gravity from
Sagittarius A*, the Milky Way’s
central supermassive black hole.Even though the magnetic field is
weaker than the gravity, the team
found that it is strong enough to
overcome turbulence in the dust
and gas and shepherd them into
the spiral shape observed.
That spiral eventually brings
the debris into orbit around
the black hole, says Dowell. He
presented the work at a meeting
of the American Astronomical
Society in St Louis, Missouri.But it seems like the magnetic
field isn’t funnelling the material
directly into Sagittarius A*,
which very rarely eats anything
substantial. We know that because
we almost never see the bright
outbursts that occur when matter
falls into a black hole.
Instead, it seems to be
channelling the gas and dust
away from the black hole’s event
horizon, the boundary around
a black hole from beyond which
nothing can emerge.
Magnetic fields are constantly
shifting, so if the field at the
galaxy’s centre changes shape,
Sagittarius A* could start feeding
again, says SOFIA team member
Joan Schmelz.
That would shake up the
Milky Way, resulting in huge
amounts of radiation and
powerful winds that could blow
material right out of the galaxy,
a phenomenon we have seen in
other, more active galaxies.
Thankfully, Earth is far enough
away from the galactic centre
that it wouldn’t affect us, says
Farhad Zadeh at Northwestern
NA University in Illinois. ❚SA
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TELE
SC
OPEPsychology
LIVING at the border between
wakefulness and a dream world
may do wonders for your creativity.
People with narcolepsy are
excessively sleepy during the day
and can often drift off. Isabelle
Arnulf, who treats narcolepsy at
Pitié-Salpêtrière Hospital in Paris,
noticed that her patients seemed
remarkably creative. Many of them
were artists and poets, for example.
“Even when they were sitting in the
waiting room, they were doodling
and writing,” she says.
Arnulf and her colleagues
asked 185 people with narcolepsy
to complete a questionnaire
designed to test for creativity.
They compared the results with
those of 126 people who didn’t
have the condition. Thirty
volunteers from each group also
undertook a creativity test, which
involved trying to find new solutions
to problems, as well as creative
writing and drawing.
People with narcolepsy did
better on every measured aspect
of creativity. For instance, whenparticipants were asked to come
up with a story that ended with the
words “... and the last apple fell from
the tree”, most composed a version
that included Adam and Eve, Isaac
Newton or the end of summer.
But the most creative responses
came from people with narcolepsy,
including a story about trees joining
a strike initiated by animals who
had decided not to feed humans
anymore, and another abouta bulimic worm called Jean-Jacques
(Brain, doi.org/c645).
Arnulf thinks this could be
because people with narcolepsy
experience an unusual sleep cycle.
A typical cycle begins with a period
of non-REM sleep, but people with
narcolepsy usually fall straight into
REM sleep – the period when we
tend to experience vivid dreams.
Penny Lewis at Cardiff University
in the UK agrees. “We think REM
sleep helps you make links between
things that are not obviously linked,
and that’s what creativity is all
about,” she says. ❚
Jessica HamzelouSpace
Leah Crane
Our galaxy’s central black hole is
oddly quiet – now we may know why
The lines show streams of
dust being pulled around
the Milky Way’s black hole“ REM sleep helps you
make links between
things and that’s what
creativity is all about”People with
narcolepsy seem to
be more creative