28 September 2019 | New Scientist | 7“The app tracks facial
movements, as well as
the content, tone and
pitch of a person’s speech”TWO recently discovered
galaxies just don’t make sense.
If they are relatively distant, the
clusters of stars in them are too
bright. If they are closer, they
must be moving too fast.
In 2018, a group led by Pieter
van Dokkum at Yale University
announced that it had found a
strange galaxy that seemed to
contain very little dark matter, or
possibly none at all. The galaxy
is known as DF2. A year later, the
group said it had discovered
another one, called DF4.
Both galaxies have a low
concentration of stars and this
wispiness makes it hard to say
how far away they are. We work
out the characteristics of galaxies,
like how much dark matter and
how many stars they have, partly
by measuring how bright and
how far away they are.
If the galaxies are about
65 million light years away, as
van Dokkum’s team originally
estimated, they appear to lack
dark matter, and clumps of stars
within the galaxies called globular
clusters are far bigger and brighter
than any we have seen before.
If the galaxies are closer, as
others have since claimed, they
are more normal, but unusually
large and moving strangely fast.
Now Moritz Haslbauer at the
University of Bonn in Germany
and his colleagues have
performed an analysis of the
DF2 galaxy. The group focused on
that one because we have more
data on it than we do for DF4.
Haslbauer’s team used five
simulations of the universe as we
know it, following it as it grew to
maturity. The physics that went
into each is slightly different.For example, some include the
effects of magnetic fields while
others don’t. The team then
searched these simulations for
galaxies that looked similar to
DF2 at various distances from us.
Very few were a good match,
and those the group did see were
most commonly about 37 million
light years away. But even in the
simulation where DF2-like
galaxies were most common,there was only a 0.01 per cent
chance of finding one at that
distance. The chance of finding
one 65 million light years away
from us was more than 200 times
lower than that (arxiv.org/abs/
1909.04663).
This means, says Haslbauer, that
DF2 and DF4 are inconsistent with
our standard model of cosmology.
Other astronomers say the
problem might just be with the
simulations, not with our model
of cosmology. “These galaxies are
definitely interesting, definitely
weird,” says Marla Geha at Yale
University. “I would put my
money on the simulations being
a little wrong rather than the
overall paradigm.”
Measurements from the
Hubble Space Telescope may soon
resolve the dispute over how far
away these wispy galaxies are.
The measurements should at
least be able to tell us in what
way the galaxies are strange.
“No matter what the distance
is, these galaxies are somehow
special,” says Ignacio Trujillo
at the Institute of Astrophysics
of the Canary Islands. ❚Astronomy
Leah Crane
NASA
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YA
LE
UNIVERS
ITY)Medical technology
Smartphone app
could spot signs
of schizophrenia
SPEAKING into your smartphone
for 2 minutes could reveal whether
you have a mental health condition.
That is according to the developers
of an app that analyses facial
expressions and speech to diagnose
schizophrenia.
The company behind the app,
AICure, hopes it could be used to
better support and monitor people
with schizophrenia, and eventually
those who have other mental health
conditions. The current version was
developed to measure symptoms
of schizophrenia like low mood
and difficulty thinking, says Isaac
Galatzer-Levy at AICure. These
are normally harder to measure
than symptoms like hallucinations
and delusions, he says.
To do this, the app tracks facial
movements, as well as the content,
tone and pitch of a person’s speech.
Some people with schizophrenia
move more slowly, and show
less emotion on their faces, says
Galatzer-Levy. The app can then
send a score to the person’s doctor,
rating these symptoms. However,it isn’t designed to spot other
symptoms associated with the
condition, such as hallucinations.
The team tested the app with
21 people who have schizophrenia
and nine people who don’t.
The participants made weekly
recordings over 12 weeks.
Each person was also evaluated
by a clinician at Mount Sinai
Hospital in New York at the
start and end of the study.The results of this trial suggest
that the app’s ratings “are highly
correlated” with those of a clinician,
says Galatzer-Levy, who presented
the work at the European College of
Neuropsychopharmacology annual
meeting in Copenhagen, Denmark.
However, AICure doesn’t yet
have enough data to prove its app
works, because the sample size
is very small, says Saeed Farooq
at Keele University, UK.
“We see these results as
proof of concept more then as
a complete diagnostic model,”
says Galatzer-Levy. ❚
Jessica HamzelouBizarre galaxies can’t be
explained by standard physics
The DF2 galaxy’s few
stars are scattered
throughout this picture