- 4167 - DARK
MATTER - is it warping our galaxy ? Our entire Milky Way galaxy is warping,
and a gigantic blob of dark matter could be to blame. An invisible halo of misaligned dark matter
could explain the warps at the Milky Way's edges.
-
--------------------
4167 - DARK MATTER
- is it warping our galaxy ?
-
- The Milky Way
galasxy isn't flat; it's warped. A new study suggests an invisible halo of dark
matter could explain why. Scientists
initially believed that the Milky Way was a flat disk dominated by two spiral
arms trailing stars from a central bar, but measurements taken since the
mid-20th century reveal that it's bent inexplicably out of shape.
-
- The warping occurs
mostly at our galaxy's borders, where some regions bend downward while others
flare upward. Now, computer simulations may have revealed the cause: a
mysterious event that knocked our galaxy's invisible halo of dark matter out of
alignment.
-
- Dark matter is a
mysterious and somewhat contradictory type of matter. It makes up 85% of the
universe's matter; but because it doesn't directly interact with light, it is
completely invisible.
-
- However,
scientists can observe its gravitational effects on its surroundings. Dark
matter makes its presence known by accelerating stars to otherwise inexplicable
speeds as they orbit galactic centers; warping distant starlight; and by giving
shape to the Milky Way's galactic halo.
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- The galactic halo
rests just beyond the spiral arms of the Milky Way. In a 2022 study,
astronomers investigated this region using the European Space Agency's Gaia
spacecraft, which maps the positions and movements of the Milky Way's roughly 2
billion stars. They discovered that the
stars suspended in the galactic halo were strangely off-kilter.
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- To see what an
unbalanced stellar halo might mean for the dark matter halo it is suspended in,
the researchers used a computer model to recreate a young Milky Way-like galaxy
with a dark matter halo tilted 25 degrees with respect to its disk. After simulating
the galaxy over 5 billion years, the researchers found that they had created a
very similar galaxy to our own.
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- What caused the
dark matter around our galaxy to fall out of tilt isn't clear, but the
researchers' simulations suggest it is likely to have been a gigantic
collision, likely from another galaxy flying into our own. This collision could
have caused the dark matter halo to tilt up by as much as 50 degrees before
slowly swinging down to its current 20-degree angle elevation.
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-
September 26, 2023 DARK MATTER
- is it warping our galaxy ? 4167
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Tuesday, September 26, 2023 ---------------------------------
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