Just as basketball scouts discover a nimble, extra-tall teenager, astronomers using the James Webb Space Telescope recently reported that they’ve identified a small, captivating group of baby galaxies near the dawn of time. According to scientists, these galaxies could grow into one of the largest mass conglomerates in the universe, a vast cluster of thousands of galaxies and trillions of stars.
The seven galaxies they identified date back to 13 billion years ago, just 650 million years after the Big Bang.
“It really could have been the most massive system in the entire universe at that time,” said Takahiro Morishita, an astronomer at the California Institute of Technology’s Center for Infrared Processing and Analysis. He described the protocluster as the most distant and therefore the earliest such entity yet observed. dr. Morishita was lead author of a report on the discovery published Monday in The Astrophysical Journal Letters.
The scientists’ report is the result of a larger effort known as the Grism Lens-Amplified Survey from Space, organized by Tommaso Treu, an astronomer at the University of California, Los Angeles, to obtain early science results from the Webb telescope.
The telescope was launched into orbit around the sun on Christmas Day 2021. With its infrared detectors and booming primary mirror, which is 21 feet wide, it is ideal for studying the early years of the universe. As the universe expands, galaxies so far away in space and time are racing away from Earth so fast that most of their visible light and information about them is stretched into invisible infrared wavelengths, like distant sirens lowering their pitch.
In its first year, the Web has already recovered many bright galaxies and large black holes that formed just a few hundred million years after the Big Bang.
The youngest infant galaxies had been discovered by the Hubble Space Telescope over the years as red points of light that were only visible at such a great distance because they were magnified by the distorting gravity of the Pandora Cluster, which is located in the constellation of the Cluster of Galaxies. Sculptor.
Spectroscopic measurements with the Webb telescope confirmed that the seven points were galaxies and were all equally distant from Earth. They occupy a region of space 400,000 light-years in diameter, or about one-sixth the distance from here to the Milky Way’s closest cousin, the large spiral galaxy Andromeda.
“So our efforts to follow up on a previously known potential protocluster finally paid off after almost 10 years!” Dr. Morishita wrote.
According to estimates based on prevailing models of the universe, gravity will eventually pull these galaxies together into a massive cluster of at least a trillion stars. “We can see these distant galaxies as small drops of water in different rivers, and we can see that eventually they will all become part of one big, mighty river,” said Benedetta Vulcani of the Italian National Institute of Astrophysics and member. to the research group.
The spectroscopic data also allowed Drs. Morishita and his colleagues determined that the stars inhabiting some of these embryonic galaxies were surprisingly mature and contained large amounts of elements such as oxygen and iron that would have had to be forged in generations of nuclear furnaces. of the earliest stars. Others among the infant galaxies were more ancient. In theory, the first stars in the universe would have been composed of pure hydrogen and helium, the first elements to emerge from the Big Bang.
Some of these galaxies produced stars at prodigious rates, more than 10 times faster than the Milky Way, which is 10 to 100 times larger. Others in the new group produced barely one star per year, “which is an interesting diversity of galaxies at this early epoch,” said Dr. Morishita.
All this raises the suspicion among some cosmologists that the early universe produced stars, galaxies and black holes much faster than standard theory predicts. In the e-mail Dr. Morishita said there is no “crisis” in cosmology yet.
“The simplest explanation,” he wrote, “is that our previous understanding of star formation and dust formation in the early universe, which are complex phenomena, was incomplete.”
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