Just like the infants of the universe, galaxies in the young universe were messy and difficult to settle down, a new study shows.
Using the powerful James Webb Space Telescope (JWST), scientists have observed more than 250 galaxies in the early universe. The researchers charted the movement of gas long ago when the universe was growing, between 800 million and 1.5 billion years after the Big Bang. (The age of the universe is approximately 13.8 billion years.)
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“The majority of the galactic population is undergoing a turbulent phase in its evolutionary history,” lead author Laura Dunhive, a doctoral candidate at the Kavli Institute for Cosmology at the University of Cambridge, told Live Science via email.
Unlike past studies, the team targeted low-mass galaxies, revealing what they called a “messy kinematics,” Danhive explained. This means that the galaxy the researchers studied is not stable like the Milky Way and its neighbors, but rather a rotating disk.
Professor Danhive added that turbulence during the early stages of the universe’s history was much higher than scientists previously thought, as earlier studies were biased toward larger, more ordered galaxies, which are easier to detect with telescopes than the smaller galaxies targeted in the new study.
“We believe that this turbulence [galaxy] “The disk is caused by a large amount of gas, which promotes intense star formation and causes gravitational instability,” Danhive said.
Additionally, the researchers illustrated how galaxies change from these chaotic structures to the more regular patterns seen in mature galaxies, providing an unprecedented view of how galaxies grow from youth to adulthood.
“Early galaxies go through a turbulent assembly phase in which strong bursts of star formation and large amounts of gas disrupt the orderly motion of the gas disk,” Danhive said. “Over time, the mass of the galaxy increases and becomes more stable.”
Structures like the Milky Way formed recently, over the past few billion years, as available gas was taken up by stars and diminished across the galaxy. Because there is less free-floating gas, mature galaxies are able to grow and change more smoothly than when they are young.
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This research would not have been possible without JWST, which is located in a remote, gravitationally stable location in space, far from the stray light of Earth and the Moon. This infrared telescope can peer deeper into the universe than any previous telescope and regularly discovers galaxies believed to be the oldest in the known universe. Danhive said the observatory, combined with simulations, is helping researchers better understand how “burst” star formation and gas affect the galactic disk.
“Overall, our study opens the door to the dynamics of early galaxy formation,” she said. Next, the research team plans to study the inflow and outflow of gas in individual galaxies by tracking how the gas becomes chemically enriched.
The researchers expect that the incoming gas will be less concentrated, or “pure” gas, thanks to contributions from individual stars in the galaxy, while the outgoing gas will have more chemical components. By studying how gas flows across galaxies, researchers may be able to understand, for example, why some galaxies rotate faster than others.
“JWST’s amazing capabilities have much to reveal, and we look forward to investigating even more aspects of early galaxy formation,” said Danhive.
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