The Webb telescope shows tantalizing views of the early universe
Just over a year after its historic launch, NASA James Webb Space Telescope JWST challenges astronomers’ predictions of the early universe and shows that massive galaxies likely formed much earlier than expected.
JWST sees in the run Infrared part of the electromagnetic spectrum invisible to our eyes, according to NASA. This means that the telescope is optimized for catching light from the early universe, which was stretched toward these longer, redder wavelengths as the universe expanded over time – a process known as redshift.
Galaxies can come in many different types, including beautiful spiral galaxies like our own Milky Wayas well as oval or irregular types, astronomy Cihan Kartaltepe of the Rochester Institute of Technology in New York said during a news conference at the 241st meeting of the American Astronomical Society in Seattle, Washington.
She added that the Hubble Space Telescope had already observed all the different types of galaxies 11 billion years ago, which indicates that their formation may have occurred even earlier. Some researchers think the James Webb Space Telescope may finally glimpse these early stages of galaxy formation because the telescope sees more into cosmic history than the Hubble telescope.
She and her team analyzed 850 galaxies between 11 and 13 billion years ago, and classified them according to whether they were spiral, elliptical, irregular, or a combination of the three. They found that the percentage of each type of galaxy remained roughly the same in the modern universe throughout that time period.
This indicates that galaxies were already fairly mature even at this point in cosmic history, Kartaltepe said. “We’re not really seeing the first galaxy formation yet,” she added. Her team’s findings have been accepted for publication in The Astrophysical Journal, to me Rochester Institute of Technology.
The oldest galaxies in the universe?
Another puzzling view of the early universe came from an astronomer Huajing Yan from the University of Missouri. He and his colleagues looked at One of the first shots of JWST – a field of stars, galaxies and galaxy clusters known as SMACS 0723 – and pinpointed some of the oldest galaxies ever observed.
Yan’s team identified 87 galaxies in this field that may have existed between 200 and 400 million years ago. .the great explosion, a very early era to see many galaxies. More analysis would be needed to confirm that these primordial galaxies did indeed exist at such early times, but Yan said he “bet 20 bucks and a beer” that at least half of them would end up correctly positioned in such ancient days.
Yan added that while many researchers thought the JWST would find at least a few galaxies that date back so far into the history of the universe, few expected them to turn up that much. He said, “Even if only a small fraction turns out to be real, the picture we previously favored of galaxy formation in the early universe must be revised.”
Yan declined to speculate on what might cause galaxies to form much earlier than expected in the universe, but said it is now up to theorists to come up with plausible explanations for such observations. His team’s work appeared in Astrophysical Journal in December.
Green peas since the dawn of time
Astrophysicist James Rhodes NASA’s Goddard Space Flight Center in Greenbelt, Maryland, gave one last look at the early universe during the AAS press conference. He and his colleagues also analyzed the deep field image of JWST’s SMACS 0723, and identified three small galaxies whose chemical compositions match very closely with a rare type of galaxy nicknamed “the green pea.”
First spotted by citizen scientists working with Galaxy Zoo in 2009, the green pea galaxies are very small — about 5,000 light-years across, or only 20 the size of the Milky Way — and are home to a great deal of star formation, Rhodes said. .
Green peas are rare, making up only 0.1% of all nearby galaxies, and are extremely pure, according to NASA. As the stars burn hydrogen And heliumThey form heavier elements like oxygen and carbon, and as they die they fling such elements across the galaxy. But green peas contain very low levels of the heavy element, which contains nearly a fifth of the Milky Way’s oxygen, similar to the three objects JWST has observed.
“We found what may be the most chemically primitive of galaxies,” Rhodes said during the press conference, adding that astronomers can use their modern counterparts to study these ancient outliers and learn more about the early universe. Results appeared on January 3rd Astrophysical Journal Letters.
Rhodes suggested that the modern green pea galaxies may be “a bit like the living fossils of the early galaxy formation. Coelacanths, if you will”, referring to kind of fish It was thought to be extinct until it was found off the coast of South Africa in 1938.