Four discoveries from the Webb telescope about distant galaxies

Diptych for GLASS-z11 and GLASS-z13

Astronomers have found these two distant galaxies in the same small part of the sky. They estimate that the person on the right dates back to 300 million years after the Big Bang.Credit: JWST GLASS Survey NASA/CSA/ESA/STScI; Pascal Oche / University of Geneva

NASA built the state-of-the-art James Webb Space Telescope to look into the distant universe and back toward the dawn of time — and it’s already doing so spectacularly. In the past two weeks since Webb’s first scientific images and data became available for astronomers to work with, they have reported a torrent of preliminary discoveries, including several contenders for what could be the most distant galaxy ever seen.

Webb’s images reveal a wealth of shimmering galaxies in the distant universe, appearing as they did a few hundred million years after the Big Bang 13.8 billion years ago. Stunningly sharp telescope images have shattered astronomers’ preconceptions about the early universe.

“We had an idea of ​​which galaxies are in these [distances] “It’s going to look like, how much detail we’ll be able to see, but I think reality is just kind of blowing our minds,” says Jehan Kartaltepe, an astronomer at Rochester Institute of Technology in New York.

Here are some of the things astronomers learn from Webb’s first observations.

There are a lot of galaxies out there.

Because Webb detects infrared light, and because the expansion of the universe stretches light to red wavelengths, the telescope is well suited for discovering galaxies that formed early in the history of the universe. In the first observational programs, which launched in June, Webb discovered many distant galaxies that lie out of reach of other observatories, such as the Hubble Space Telescope.

“It indicates what many of us have been arguing, that there are galaxies out there that are 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,” perhaps about 250 million years after the Big Bang, when the first stars formed and lit up the universe. Subsequent generations of stars coalesced into galaxies, the faint red dots that Webb began to discover.

Many of Webb’s images permeate never-before-seen galaxies in the distant universe. “There is hardly any empty space that has nothing,” Kartaltepe says.

One study combed data from many of the distant galactic domains that Webb has observed so far, to analyze the rate at which stars formed in the early universe. It found 44 previously unknown galaxies stretching back 300 million years from the Big Bang. Combined with 11 previously known galaxies, the results show that there were a large number of star-forming galaxies in the early universe.1. The results “reaffirm the enormous potential of the next greatest [Webb] Programs to transform our understanding of the young universe,” the team led by Callum Dunant of the University of Edinburgh, UK, wrote in a research paper on the arXiv preprint server.

Several galaxies are vying for the “furthest” title.

Perhaps the biggest rush is that of research teams vying to locate the most distant galaxy in Webb’s data. A number of candidates have been spotted that will need to be confirmed by further studies, but they all will break Hubble’s record for the most distant galaxy, dating back about 400 million years after the Big Bang.2And the3.

Pixelated image of Macy's Galaxy

Macy’s Galaxy: Astronomer Stephen Finkelstein named this distant galaxy after his daughter. It is estimated to date back to 280 million years after the Big Bang.Credit: Stephen Finkelstein (Utah Austin), Michaela Bagley (Utah Austin), Casey Papovich (Texas A&M) and the CEERS team

A contender featured in a web survey called GLASS that included another galaxy, slightly less distant, in the same image.4. “The fact that we found these two bright galaxies was really surprising,” says Marco Castellano, an astronomer at the National Institute of Astrophysics in Rome. He and his colleagues had not expected to find any distant galaxies in this small part of the sky. A second team also independently observed the two galaxies5.

Astronomers characterize the distance of galaxies by a scale known as the redshift, which quantifies how much light has been converted into red wavelengths. The greater the redshift, the greater the distance to the galaxy. The GLASS filter has a redshift of approximately 13. But on July 25 and 26, days after astronomers reported the GLASS galaxies, papers claiming redshift flooded above the arXiv server before printing. “This is just the beginning of the beginning,” says Rohan Naidoo, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.

One candidate, at a redshift of 14, appeared in a survey called CEERS, one of Webb’s most notable early projects. CEERS principal investigator Stephen Finkelstein at the University of Texas at Austin named the Maisie’s Galaxy, after his daughter.6. Another study looked at the first deep-field image from the Webb, released by US President Joe Biden on July 11, and found two possible galaxies at a redshift of 16, placing them just 250 million years after the Big Bang.7. Other arXiv papers predict other candidates, even at a redshift of 20 .8.

Some of the early galaxies are surprisingly complex.

It also turns out that the distant Webb galaxies have more structure than astronomers expected.

One study of Webb’s first deep-field image found a surprisingly large number of distant galaxies forming as disks.9. Using Hubble, astronomers have concluded that distant galaxies are more irregularly shaped than nearby galaxies, which, like the Milky Way, often display regular shapes like disks. The theory was that early galaxies were often distorted by interactions with neighboring galaxies. But Webb’s observations indicate that there are as many as 10 times as many disc-shaped galaxies as previously thought.

The first deep field image from the James Webb Space Telescope

US President Joe Biden released this in-depth photo on July 11 – the first publicly revealed science view from Webb.Credit: NASA, ESA, CSA, and STScI

“Thanks to James Webb’s accuracy, we can see that galaxies have disks much earlier than we thought,” says Alison Kirkpatrick, an astronomer at the University of Kansas in Lawrence. It’s a problem, she says, because it goes against previous theories of galactic evolution. “We’ll have to find out.”

The preprint manuscript indicates that massive galaxies formed much earlier in the universe than previously known. A team led by Ivo Labe of Swinburne University of Technology in Melbourne, Australia, reports the presence of seven massive galaxies in the CEERS field, with a redshift between 7 and 1010. The scientists wrote: “We conclude that the central regions of at least some massive galaxies did exist to a large extent 500 million years after the Big Bang, and that massive galactic formation began very early in the history of the universe.”

Studies of galactic chemistry also show a rich and complex picture emerging from Webb’s data. One analysis of the first deep-field image examined light emitted by galaxies at a redshift of 5 or more. (The spectral lines that appear at different wavelengths of light are related to the chemical elements that make up galaxies.) And it found a surprising richness in elements like oxygen.11. Astronomers thought the chemical fertilization process — in which stars fuse hydrogen and helium to form heavier elements — took some time, but finding it underway in early galaxies “will make us rethink the speed at which star formation occurs,” says Kirkpatrick.

The nearest galaxies are smaller than expected.

Surprises from Webb continue a little later in the evolution of the universe. One study looked at Webb’s observations of a “cosmic noon,” a period of nearly 3 billion years after the Big Bang. This is the time when star formation in the universe reached its peak, and most of the light was produced.

Wren Suess, an astronomer at the University of California, Santa Cruz, compared Hubble images of galaxies at cosmic noon with Web images of the same galaxies. At the infrared wavelengths detected by Webb, most massive galaxies appeared much smaller than in the Hubble images.12. “It potentially changes our whole view of how the sizes of galaxies evolve over time,” Seuss says. Hubble studies suggested that galaxies start out small and grow larger over time, but Webb’s results suggest that Hubble didn’t have the full picture, so the evolution of galaxies may be more complex than scientists expected.

With Webb at the start of over 20 years of planned work, astronomers know they have plenty of changes ahead. “Right now I find myself lying awake at 3 in the morning wondering if everything I did was wrong,” says Kirkpatrick.

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