- 4402
- DARK MATTER TESTS
- Most, if not all galaxies
are surrounded by halos of this mysterious, unknown, but ubiquitous
material. This stuff also played a role
in galaxy formation. The nature of that role is something astronomers are still
figuring out. Today, they’re searching the infant Universe, looking for the
tiniest, brightest galaxies. That’s because they could help tell the tale of
dark matter’s role in galactic creation.
------------------------------------------------ 4402 -
DARK MATTER TESTS
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- Computer models take into account
previously neglected interactions between dark matter and the primordial
“stuff” of the Universe. That would be hydrogen and helium gas. The result of
the simulations mean tiny, bright galaxies that formed more quickly than in
computer models that didn’t include those motions. Now astronomers just need to
find them, using JWST, in an effort to see if their theories of dark matter
hold up.
-
- “Dark Matter” Interactions with “Supersonic
Baryonic” interactions between baryonic matter in the early Universe. The clouds of gas moved at supersonic
speeds past clumps of dark matter. It bounced off the dark matter. Eventually,
after millions of years, the gaseous material fell back together to form stars
in a blast of star birth.
-
- The existence of those smaller, brighter,
more distant galaxies could confirm the so-called “cold dark matter” model. It
suggests that the Universe was in a hot dense state containing only gases after
the Big Bang. Over time, it evolved to a lumpy distribution of galaxies and
eventually galaxy clusters. Along the way, stars and galaxies formed, but the
earliest steps likely depend on gravitational interaction with dark matter.
-
- JWST has seen some early galaxies during
its time in operation. It hasn’t detected the very earliest ones—yet. However,
the images it has provided are tantalizing hints at what might exist in earlier
epochs and could provide insight into the role of dark matter. So, it makes
sense that astronomers want to push its view back in time as far as they can.
And, that means looking for bright patches of light that existed a few hundred
million years after the Big Bang.
-
- The discovery of patches of small, bright
galaxies in the early universe would confirm that we are on the right track
with the cold dark matter model because only the velocity between two kinds of
matter can produce the type of galaxy we’re looking for. If dark matter does not behave like standard
cold dark matter and the streaming effect isn’t present, then these bright
dwarf galaxies won’t be found and we need to go back to the drawing board.
-
- JWST will begin to look for galaxies that
are much brighter than expected. If they exist, that will likely prove the
interactions occurred early in cosmic time. If none can be found, then maybe
scientists still might not understand dark matter interactions.
-
- The standard cosmological model says that
the gravitational pull of clumps of dark matter in the early Universe attracted
ordinary matter. Eventually, that caused stars to form, followed by galaxies.
Dark matter is thought to move more slowly than light. So, astronomers
predicted that the star- and galaxy-formation processes happened very
gradually.
-
- But, what if something else was going on
more than 13 billion years ago? How would that change things? It was a time
before the first galaxies formed. But, it was a time when ordinary matter in
the form of large over densities of hydrogen and helium gas streamed through
the expanding Universe. It bounced off slower-moving clumps of dark matter and
outran its gravitational pull, at least for a time. Then, the baryonic matter
massed together again, under the influence of dark matter. That’s when the star
birth fireworks began.
-
- While the streaming suppressed star
formation in the smallest galaxies, it also boosted star formation in dwarf
galaxies, causing them to outshine the non-streaming patches of the universe. The accumulated gas began to fall together
after millions of years. That led to a huge burst of star formation. Lots of
massive hot, young stars began to shine, out-brilliancing the stars in other
small galaxies. Ultimately what this means is that since dark matter is
impossible to “see”, those brightly shining patches of galaxies could be
indirect evidence of its existence.
-
- The discovery of patches of small, bright
galaxies in the early universe would confirm that we are on the right track
with the cold dark matter model because only the velocity between two kinds of
matter can produce the type of galaxy we’re looking for.
-
- JWST should be able to peer into regions
of the Universe where tiny infant galaxies are brighter than astronomers expect
them to be. That extreme luminosity will
help JWST spot them, showing them as they looked at a time when the Universe
was only a few hundred million years old. Because dark matter is impossible to
study directly, searching for those bright patches of baby galaxies in the
early Universe could offer an effective test for theories about dark matter and
its role in shaping the first galaxies.
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-
March 24, 2023 DARK
MATTER TESTS
4402
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------ “Jim Detrick” -----------
--------------------- --- Monday, March 25, 2024
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