WASHINGTON, Oct 6 (Reuters) – Since it began operating last year, the James Webb Space Telescope has uncovered a collection of galaxies dating back to a mysterious era known as the dawn of the universe, revealing surprising glimpses of the universe’s early history. It has provided a glimpse.
However, the existence of what appeared to be giant, mature galaxies in the early universe defied expectations. It was too big, too soon. This has left scientists scrambling for explanations, questioning the fundamental tenets of cosmology, the science of the origin and development of the universe. New research may solve the mystery without breaking the textbook.
Researchers used advanced computer simulations to model how the earliest galaxies evolved. These studies show that in the first few hundred million years after the Big Bang, which marked the beginning of the universe 13.8 billion years ago, star formation in these galaxies was different than in large galaxies like the Milky Way that exist in the universe today. shows what happened.
They discovered that star formation in early galaxies did not occur at a steady pace, but in occasional large bursts. This is important because scientists typically use a galaxy’s brightness to measure its size, or its collective mass of millions or billions of stars.
So while these galaxies may have been relatively small, as expected, their bright bursts of star formation made them shine as brightly as truly massive galaxies, giving rise to the deceptive idea that they were massive, according to the study. It may make an impression.
“Because photons (particles of light) can be directly detected and counted, astronomers can reliably measure how bright these early galaxies were, but it is unclear whether these galaxies were really large or gigantic. It’s much harder to tell. They appear larger because they’ve been observed to get brighter,” said the author, a postdoctoral fellow in astronomy at Northwestern University in Illinois, in the Astrophysical Journal Letters this week. said Guchao Sun, lead author of the published study.
Webb, launched in 2021 and operational in 2022, has detected about 10 times more extremely bright galaxies since the dawn of the universe than expected based on most theoretical models.
“According to the standard model of cosmology, there should not be many very large galaxies at the dawn of the universe because it takes time for galaxies to grow after the Big Bang. Immediately after the Big Bang, the universe was very hot and almost homogeneous. “It was a plasma, a fireball, and there were no stars or galaxies,” said Claude-Andre Faucher Giguère, an astrophysicist at Northwestern University and lead author of the study. Told.
“Our new paper uses simulations to quantitatively show that bursts of star formation produce flashes that can explain the very bright galaxies observed by Webb. “This is because we can explain these extremely bright galaxies, “breaking the standard cosmological model,” Faucher-Giguere added.
The simulations in this study were conducted as part of the Feedbacks in the Relativistic Environment (FIRE) research project.
The discovery focused on a phenomenon called “burst star formation.”
“In contrast to stars forming at a nearly constant rate, star formation activity in these early galaxies was intermittent, with large fluctuations over time. This explains why the Milky Way “This causes large fluctuations in star-forming activity,” Sun said, “because the light you see with telescopes like JWST comes from young stars that formed in those galaxies.”
Researchers have an idea why this phenomenon occurs in small galaxies. In these, very large stars form suddenly and explosively, and because of their size can explode as supernovae after only a few million years. They inject gas into space, which becomes the material for further star formation. However, in larger galaxies, stronger gravitational effects prevent these outbursts, favoring stable star formation.
Sun hopes that Webb will continue to challenge our understanding of the universe and provide fresh insights, whether or not they meet scientific expectations.
“This is exactly how science is done and progresses,” Sun said.
Reporting: Will Dunham; Editing: Rosalba O’Brien
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