The James Webb Telescope (JWST or Webb) has discovered hundreds of ancient galaxies that could be among the first members of the universe – just a few hops from what was known to exist at the time.
600 million years later Big bang, these very young galaxies showed complex structures and clusters of star formation, a new study reports. The study is part of an international collaboration called the JWST Advanced Deep Extragalactic Survey (JADES), which collected a month of observations from two small spots in the sky: one in the constellation Ursa Minor and the other in the direction of the Fornax cluster. There were more than 700 newly discovered young galaxies in the region, which together with the cosmos appeared to be the earliest.
“If you take the entire universe and condense it into a two-hour movie, you’ll see the first five minutes of the movie,” said Kevin Heinlein, assistant professor of science at the Steward Observatory in Arizona and lead author of the new study. , said Monday (June 5) when announcing the discovery at the 242nd meeting of the American Astronomical Society in Albuquerque and online. “These galaxies begin the process of creating the elements and the complexity we see in the universe around us today.”
These new findings reveal how the first galaxies and stars formed, creating a rich catalog of elements observed in today’s universe.
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During those five minutes, which indicate that the universe is between 370 million and 650 million years old, Heinlein and his colleagues examined 717 young galaxies in the Webb data, which turned out to be higher than previous estimates, which included thousands of galaxies in total. light years, sports complex structures and birth stars in several clusters.
“The earliest galaxies we’ve ever seen look like tiny specks. But these specks represent millions, if not billions, of stars in the early universe,” Heinlein said. statement. “Now we see that some of them are extended objects with visible structure.”
The two regions used in this study are collectively referred to as GOODS-South, an acronym Large observatories start with deep researchand has been extensively studied by almost all major space telescopes, including Hubblethe Chandra X-ray Observatory and NASA’s now-retired Spitzer.
Despite this previous verification, 93% of the new galaxies Webb observed during JADES had never been seen before.
“What we’ve seen before are the brightest, most extreme examples of bright galaxies in the early universe,” Heinlein said in his presentation on Monday. “Now we’re really studying normal, everyday galaxies in a turbulent young universe.”
It has long been debated how this chaotic, extremely dusty environment was cleaned up and transformed into the transparent cosmos we see today. The leading theory is the so-called phase of the evolution of the universe The era of reionizationAbout 400,000 years after the Big Bang, the first generation of stars (estimated to be 30 to 300 times the mass of the Sun and millions of times brighter) appeared and flooded the opaque universe. first light.
These ultraviolet stars re-ionized the universe by splitting its abundant hydrogen atoms into protons and electrons, a process that took up to a billion years after the Big Bang. However, few astronomers report leakage supermassive black holesmay be similar to the one located at the heart of our Milky Way caused the escape of ultraviolet radiation came from galaxies and thus played a more important role in cosmic evolution than previously thought.
Now, a second team from the JADES program is studying galaxies from 500 to 850 million years after the Big Bang, or galaxies that span five to eight minutes of a two-hour movie that describes the universe. an age-old question.
“In the next view of the universe, we’re really starting to see the effect of galaxy formation on the composition of the large-scale universe,” said Ryan Endsley, a postdoctoral researcher at the University of Texas at Austin who led the second study. press conference on Monday. “The earliest galaxies in the Universe were generally much more chaotic in their way of star formation.”
Endsley’s team studied the symptoms star formation in these very early galaxies, allowing us to understand how the gas in these galaxies is ionized by starlight. The team found that one in six galaxies at that time had extreme line emission in the galaxy’s spectra, a feature emitted when atoms ionized by starlight cool and combine with other molecules.
These emission lines are evidence that early galaxies were actively producing stars, which then pumped “waves of ultraviolet photons” into their galaxies. Thus, the universe’s first stars were the main driving force behind cosmic reionization, Endsley said.
“These extreme emission lines are relatively common in the very early universe,” he said in his presentation. “Almost every galaxy we find shows a particularly strong emission line that indicates recent star formation,” he added in a statement. “These early galaxies were very good at making hot, massive stars.”
From those emission lines, Endsley’s team concluded that galaxies in the early universe produced stars in short bursts, followed by quiescent periods.
“Suddenly you have dozens day These early galaxies immediately accumulated a solar mass’s worth, Endsley told reporters at a briefing on Monday. “This is very important to our understanding of how reionization occurred because these hot massive stars were very efficient producers of these ultraviolet photons. we needed it to ionize all the hydrogen in the early universe.”
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