Webb telescope spies likely oldest galaxies ever found, upending cosmic timeline

Two super-bright galaxies from universe’s earliest years point to stars possibly being formed 100 million years before previously thought, though more data needed to verify claim

Countless glowing galaxies of all shapes and sizes speckling the black backdrop of space. Toward the center left, a red dot, a never-before-seen galaxy discovered by Webb.(NASA/ESA/CSA/Tommaso Treu - UCLA)
Countless glowing galaxies of all shapes and sizes speckling the black backdrop of space. Toward the center left, a red dot, a never-before-seen galaxy discovered by Webb.(NASA/ESA/CSA/Tommaso Treu - UCLA)

CAPE CANAVERAL, Florida — NASA’s Webb Space Telescope is finding bright, early galaxies that until now were hidden from view, including one that may have formed a mere 350 million years after the cosmos-creating Big Bang.

Astronomers said Thursday that if the results are verified, this newly discovered throng of stars would beat the most distant galaxy identified by the Hubble Space Telescope, a record-holder that formed 400 million years after the universe began.

Launched last December as a successor to Hubble, the Webb telescope is providing observations indicating stars may have formed sooner than previously thought — perhaps within a couple million years of the creation of the universe.

Webb’s latest discoveries were detailed in the Astrophysical Journal Letters by an international team led by Rohan Naidu of the Harvard-Smithsonian Center for Astrophysics. The article elaborates on two exceptionally bright galaxies, the first thought to have formed 350 million years after the Big Bang and the other 450 million years after.

The extreme luminosity points to two intriguing possibilities, astronomers on a NASA press call said Thursday.

The first is that these galaxies are very massive, with lots of low-mass stars like galaxies today, and had to start forming 100 million years after the Big Bang.

A composite image showing two galaxies thought to be among the oldest ever observed, as seen by the James Webb Space Telescope. Inset shows galaxies up close.(NASA/ESA/CSA/Tommaso Treu – UCLA)

That is 100 million years earlier than what is currently thought of as the end of the so-called cosmic dark age, when the universe contained only gas and dark matter.

A second possibility is that they are made up of “Population III” stars, which have never been observed but are theorized to have been made of only helium and hydrogen, before heavier elements existed.

Because these stars burned so brightly at extreme temperatures, galaxies made of them would not need to be as massive to account for the brightness seen by Webb, and could have started forming later.

“We are seeing such bright, such luminous galaxies at this early time, that we’re really uncertain about what is happening here,” Garth Illingworth of the University of California at Santa Cruz, a co-author of the article, told reporters.

Although some researchers report having uncovered galaxies even closer to the creation of the universe 13.8 billion years ago, those candidates have yet to be verified, scientists stressed.

Countless glowing galaxies of all shapes and sizes speckling the black backdrop of space. Toward the bottom left, a small reddish disk is framed in a tiny white box. The red disk is another early galaxy, thought to have existed 450 million years after the Big Bang. (NASA/ESA/CSA/Tommaso Treu – UCLA)

“This is a very dynamic time,” said Illingworth, a co-author of the article. “There have been lots of preliminary announcements of even earlier galaxies, and we’re still trying to sort out as a community which ones of those are likely to be real.”

He said disentangling the two competing hypotheses would be a “real challenge,” though the Population III idea was more appealing to him, as it would not require upending existing cosmological models.

Tommaso Treu of the University of California, Los Angeles, a chief scientist for Webb’s early release science program, said the evidence presented so far “is as solid as it gets” for the galaxy believed to have formed 350 million after the Big Bang. The galaxy, called GLASS-z12, now represents the most distant starlight ever seen.

If the findings are verified and more early galaxies are out there, Naidu and his team wrote that Webb “will prove highly successful in pushing the cosmic frontier all the way to the brink of the Big Bang.”

An hourglass-shaped, multi-color cloud of dust and gas is illuminated by light from a protostar, a star in the earliest stages of formation, in an image captured by the Webb Space Telescope. In the center of the hourglass shape is a small, dark demarcation line, an edge-on view of a protoplanetary disk, a disk of material being pulled into a star as it forms. (NASA, ESA, CSA, STScI)

“When and how the first galaxies formed remains one of the most intriguing questions,” they said in their paper.

Teams are hoping to soon use Webb’s powerful spectrograph instruments — which analyze the light from objects to reveal their detailed properties — to confirm the galaxies’ distance, and better understand their composition.

Webb can detect infrared light at a far higher resolution than any instrument before it.

The $10 billion observatory — the world’s largest and most powerful telescope ever sent into space — is in a solar orbit that’s 1 million miles (1.6 million kilometers) from Earth.

This image released by NASA on October 19, 2022, shows the Pillars of Creation, captured by the James Webb Space Telescope in near-infrared-light view. (NASA, ESA, CSA, STScI via AP)

Full science operations began over the summer, and NASA has since released a series of dazzling snapshots of the universe.

The galaxies’ rapid discovery defied expectations that Webb would need to survey a much larger volume of space to find such cosmic wonders.

“It’s sort of a bit of a surprise that there are so many that formed so early,” added astrophysicist Jeyhan Kartaltepe of the Rochester Institute of Technology.

In this image provided by NASA, the James Webb Space Telescope is released into space from an Ariane rocket on Saturday, December 25, 2021. The telescope is designed to peer back so far that scientists will get a glimpse of the dawn of the universe about 13.7 billion years ago and zoom in on closer cosmic objects, even our own solar system, with sharper focus. (NASA via AP, File)

NASA’s Jane Rigby, a project scientist with Webb, noted that the galaxies “were hiding just under the limits of what Hubble could do.”

“They were right there waiting for us,” she told reporters. “So that’s a happy surprise that there are lots of these galaxies to study.”

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