The standard model predicted that the NASA/ESA/CSA James Webb Space Telescope would see dim signals from small, primitive galaxies. But data are not confirming the popular hypothesis that invisible dark matter helped the earliest stars and galaxies clump together. Instead, the oldest galaxies are large and bright, in agreement with an alternate theory of gravity, according to new research led by Case Western Reserve University astrophysicists.
“What the theory of dark matter predicted is not what we see,” said Case Western Reserve’s Professor Stacy McGaugh.
“Instead of dark matter, modified gravity might have played a role. A theory known as MOND (MOdified Newtonian Dynamics), predicted in 1998 that structure formation in the early Universe would have happened very quickly — much faster than the theory of cold dark matter, known as lambda-CDM, predicted.”
Webb was designed to answer some of the biggest questions in the Universe, such as how and when did stars and galaxies form?
Until it was launched in 2021, no telescope was able to see that deeply into the Universe and far back in time.
Lambda-CDM predicts that galaxies were formed by gradual accretion of matter from small to larger structures, due to the extra gravity provided by the mass of dark matter.
“Astronomers invented dark matter to explain how you get from a very smooth early Universe to big galaxies with lots of empty space between them that we see today,” Professor McGaugh said.
The small pieces assembled in larger and larger structures until galaxies formed. Webb should be able to see these small galaxy precursors as dim light.
“The expectation was that every big galaxy we see in the nearby Universe would have started from these itty-bitty pieces,” Professor McGaugh said.
But even at higher and higher redshift — looking earlier and earlier into the evolution of the Universe — the signals are larger and brighter than expected.
MOND predicted that the mass that becomes a…
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