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Astronomers seem to have revealed a puzzling
detail in the way dark matter behaves.

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They found small, dense concentrations of
dark matter that bend and magnify light much

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more strongly than expected.

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Dark matter is a mysterious, invisible substance
that makes up the bulk of a galaxy. The gravitational

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pull exerted by dark matter is thought to
tie galaxies together throughout the universe.

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There is so much regular matter and dark matter
concentrated in massive galaxy clusters that

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their gravity magnifies and warps light from
distant background objects.

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We call this effect “gravitational lensing.”
We can map where the dark matter is in galaxy

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clusters by observing how the light bends.

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Gravitational lensing distorts the appearance
of background galaxies into deformed shapes

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and elongated arcs. Pictures of lensing galaxy
clusters are filled with the smeared images

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of remote background galaxies.

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The higher the concentration of dark matter
in a galaxy cluster, the more dramatic its

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light-bending power is. Smaller clumps of
dark matter associated with individual galaxies

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in the galaxy cluster create more distortions.
In some sense, the galaxy cluster acts as

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a large lens that has many smaller lenses
embedded inside of it.

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But strangely, astronomers found that three
galaxy clusters used in their study had concentrations

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of dark matter that are so massive that the
lensing effects they produce are 10 times

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stronger than originally expected.

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Hubble’s crisp images, coupled with observations
from the very large telescope in Chile, helped

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astronomers produce a more accurate dark-matter
map.

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By measuring the lensing distortions, astronomers
could trace out the amount and distribution

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of dark matter.

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This recent study could signal a gap in our
current understanding of the nature of dark

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matter and its properties. It shows us that
there’s clearly a missing feature of the

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real universe that we simply are not capturing
in our current theoretical models.

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With studies like this, astronomers look forward
to continuing to pin down the intriguing nature

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of dark matter to better understand the secrets
of our mysterious universe.

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