The telescope has enabled scientists to look so far into the cosmos that they're getting close to the period when we believe the universe's first galaxies came into existence.
Get ready to rewrite the textbooks: The James Webb Space Telescope has offered a game-changing glimpse into the early universe, challenging long-held beliefs about how galaxies form.
The telescope has enabled scientists to look so far into the cosmos that they’re getting close to the period when we believe the universe’s first galaxies came into existence. Until now, the prevailing wisdom held that there was a consistent correlation between the number of stars a galaxy has formed and the amount of heavy elements it contains.
Breaking Old Assumptions
This time-tested theory is undergoing a major shake-up. For the first time, researchers are finding that this correlation doesn’t necessarily apply to the universe’s oldest galaxies. These celestial bodies appear to be in their formative stages, lacking the time needed to produce heavy elements.
As we delve deeper into space, the light from distant galaxies provides us with a visual roadmap of their evolution throughout the universe’s history. The farther away a galaxy is, the older it appears to us due to the time its light takes to reach Earth.
For about 12 billion years—roughly five-sixths of the universe’s age—galaxies seemed to be in a state of equilibrium. They displayed a stable relationship between the number of stars and heavy elements they created. In astronomical terms, “heavy elements” means anything more complex than hydrogen and helium.
The Original Cosmic Composition
The universe initially consisted only of hydrogen and helium. All other heavier elements like carbon, oxygen, and iron were manufactured later by stars. Hence, the earliest galaxies should be devoid of these heavier elements.
However, before the Webb telescope’s launch, our observational capacity had limits. The light from far-off galaxies tends to redden as it travels through space, requiring an infrared telescope to observe them. Thankfully, James Webb’s cutting-edge technology broke these barriers.
In a groundbreaking study released on September 21 in Nature Astronomy, a Danish research team from the Cosmic Dawn Center at the Niels Bohr Institute and DTU Space made some riveting discoveries. They found what seems to be some of the universe’s earliest galaxies, still in their formative phase.
A Technological Leap Forward
“James Webb has revolutionized our ability to study the universe’s fledgling galaxies,” says Kasper Elm Heintz, who led the study. “Before this, we simply didn’t have the technology to delve into this period in cosmic history.”
While star mass and heavy elements have been thought to correlate linearly, it turns out the relationship is more nuanced. Factors like the rate of new star formation also come into play, affecting the amount of heavy elements present.
Analysis of light from 16 of these ancient galaxies revealed they had significantly fewer heavy elements than their contemporary counterparts. On average, they had four times fewer heavy elements, upending the established notion that galaxies have been in equilibrium for most of the universe’s history.
Theory Meets Reality
These startling findings weren’t entirely out of left field. Computational models of galaxy formation had predicted something similar, but this is the first time we’ve been able to observe it. The probable explanation? We’re witnessing galaxies in the act of formation, as gravity begins to clump gas together to form stars.
“The results offer an unprecedented look into the early stages of galaxy formation, which seems more closely tied to the surrounding intergalactic medium than previously thought,” concludes Heintz. “Further studies with James Webb will undoubtedly offer a clearer understanding of how the universe began to take shape after the Big Bang.”
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