Four revelations from the Webb telescope about distant galaxies

Diptych of the GLASS-z11 and GLASS-z13 galaxies

Astronomers found these two distant galaxies in the same small part of the sky. They estimate that the one on the right is 300 million years after the Big JWST Glass Survey NASA/CSA/ESA/STScI; Pascal Ochs/University of Geneva

NASA builds its state-of-the-art James Webb Space Telescope peers in a distant universe And back to the dawn of time – and it’s already doing so wonderfully. In the two weeks after Webb’s first science images and data became available for astronomers to work with, he has reported a flood of preliminary discoveries, including several contenders that may be the most distant galaxy ever discovered.

Webb’s images reveal a wealth of twinkling galaxies in the distant universe, appearing a few hundred million years after the Big Bang 13.8 billion years ago. telescopic amazingly sharp photos Astronomers’ preconceptions about the early universe have been shattered.

“We had this idea in mind which galaxies are on these [distances] It will look like that, and we will be able to see how much detail, but I think the reality is going to blow our minds,” says Jehan Kartltepp, an astronomer at the Rochester Institute of Technology in New York.

Here are some things astronomers are learning from Webb’s first observations.

There are many galaxies out there.

Because Webb detects infrared light, and because the expansion of the universe expands the light to red wavelengths, the telescope is suitable for observing galaxies that formed early in the history of the universe. In his first observation programs, which began in June, Webb discovered many distant galaxies that are beyond the reach of other observatories such as the Hubble Space Telescope.

“This suggests that many of us have been arguing that there are galaxies beyond what we saw with Hubble,” says Richard Ellis, an astronomer at University College London.

The era of early galaxies began at the ‘cosmic dawn’, probably some 250 million years after the Big Bang, when the first stars formed and illuminated the universe. Subsequent generations deposited themselves into galaxies, which are the faint red blob that Webb is beginning to discover.

Many of Webb’s images are filled with never-before-seen galaxies in the distant universe. “There is hardly an empty space with nothing,” says Kartltepe.

To analyze the rate of star formation in the early universe, Webb has so far sifted through data from several distant galaxy regions. It found 44 previously unknown galaxies dating back to within 300 million years of the Big Bang. Along with 11 previously known galaxies, the findings suggest that there was a significant population of star-forming galaxies in the early universe.1, Results “re-confirm the big potential to come” [Webb] program to transform our understanding of the young universe,” wrote the team led by Callum Donnan of the University of Edinburgh, UK, in a paper on the arXiv preprint server.

Several galaxies are competing for the title of ‘farthest’.

The stampede of research teams is perhaps the most high-profile rush to identify the most distant galaxy in the Webb data. Several candidates have been observed that will need to be confirmed through further studies, but they will all break Hubble’s record of the most distant galaxy, which dates back to about 400 million years after the Big Bang.2,3,

Pixelated image of Massey's galaxy

Massey’s Galaxy: Astronomer Steven Finkelstein named this distant galaxy after his daughter. They estimate it to be 280 million years after the Big Bang.Credits: Steven Finkelstein (UT Austin), Mikaela Bagley (UT Austin), Casey Papovich (Texas A&M) and the CERS team

A contender emerged in a web survey called GLASS that included another, slightly less distant galaxy in the same image.4, “The fact that we found these two bright galaxies was really a surprise,” says Marco Castellano, an astronomer at the National Institute for Astrophysics in Rome. He and his colleagues did not expect that they would find such a distant galaxy in this small part of the sky. A second team also observed the two galaxies independently.5,

Astronomers characterize the distance to galaxies with a measurement known as redshift, which determines how much of the galaxy’s light is shifted to redder wavelengths; The greater the redshift, the farther away the galaxy is. The GLASS candidate has a redshift of around 13. But on July 25 and 26, days after astronomers reported GLASS galaxies, papers claimed that even more redshifts filled the arXiv preprint server. “This is just the beginning,” says Rohan Naidu, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.

One candidate, 14 on redshift, emerged in a survey called CEERS, one of the Web’s highest-profile early projects. CEERS principal investigator at the University of Texas at Austin, Steven Finkelstein, named the object Macy’s Galaxy after his daughter6, Another study looked at First deep-field image from the webIt was released by US President Joe Biden on July 11, and found two possible galaxies at a redshift of 16, which would place them 250 million years after the Big Bang.7, And other arXiv papers guess at other candidates even 20 . even up to redshift8,

Some early galaxies are surprisingly complex.

Webb’s distant galaxies are also more structured than astronomers expected.

A study of Webb’s first deep-field image found a surprisingly large number of distant galaxies that are disk-shaped9, Using Hubble, astronomers concluded that distant galaxies are more irregularly shaped than nearby galaxies, which, like the Milky Way, often exhibit disc-like regular forms. The theory was that early galaxies were often distorted by interactions with neighboring galaxies. But Webb observations show that the number of disk-shaped galaxies is 10 times as many as previously thought.

First deep-field image from the James Webb Space Telescope

US President Joe Biden released this deep-field image on July 11 – the first scientific view of Webb revealed publicly.Credits: NASA, ESA, CSA, and STScI

“With the resolution of James Webb, we are able to see that galaxies have disks earlier than we thought,” says Alison Kirkpatrick, an astronomer at the University of Kansas in Lawrence. She says this is a problem, as it contradicts earlier theories of galaxy evolution. “We have to find out.”

Another preprint manuscript shows that the largest galaxies previously known in the universe were formed. A team led by Ivo Labe of Swinburne University of Technology in Melbourne, Australia, reports finding seven giant galaxies in the CEERS region, with redshifts between 7 and 10.10, The scientists wrote, “We estimate that the central regions of at least some giant galaxies were already massive 500 million years after the Big Bang, and that massive galaxy formation began much earlier in the history of the universe.” “

And galactic chemistry studies also show a rich and complex picture emerging from web data. An analysis of the first deep-field image examined the light emitted by galaxies at redshifts of 5 or greater. (The spectral lines that appear at different wavelengths of light are related to the chemical elements that make up galaxies.) It was found to have an astonishing richness of elements such as oxygen.1 1, Astronomers had thought that the process of chemical enrichment – ​​in which stars combine hydrogen and helium to form heavier elements – took a while, but finding that it was going on in early galaxies “would have us rethinking the speed at which stars move”. builds up”, Kirkpatrick says.

Nearby galaxies are smaller than expected.

The wonder from the web continues a little later in the evolution of the universe. One study looked at Webb’s observations of a ‘cosmic noon’, a period roughly 3 billion years after the Big Bang. This is when star formation in the universe was at its peak, and most of the light was created.

Wren Souss, an astronomer at the University of California, Santa Cruz, compared Hubble images of galaxies at cosmic noon to Webb images of the same galaxies. At infrared wavelengths discovered by Webb, most massive galaxies looked much smaller than in Hubble images12, “This potentially changes our whole view of how the shape of a galaxy evolves over time,” Sous says. Hubble studies suggested that galaxies start out small and get bigger over time, but Webb’s findings indicate that Hubble didn’t have the full picture, and so galaxy evolution may be more complex than scientists expected. .

At the start of more than 20 years of planned work with Webb, astronomers know they have plenty of changes ahead. “Right now I find myself waking up at three in the morning,” Kirkpatrick says, “thinking everything I’ve done was wrong.”

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