James Webb telescope discovers the 2 earliest galaxies in the known universe — and 1 is shockingly big

Astronomers find most distant galaxy using James Webb Space Telescope

An international team of astronomers today announced the discovery of the two earliest and most distant galaxies ever seen, dating back to only 300 million years after the Big Bang. These results, using NASA's James Webb Space Telescope (JWST), mark a major milestone in the study of the early universe.

The discoveries were made by the JWST Advanced Deep Extragalactic Survey (JADES) team. Daniel Eisenstein from the Center for Astrophysics | Harvard & Smithsonian (CfA) is one of the team leaders of JADES and Principal Investigator of the observing program that revealed these galaxies. Ben Johnson and Phillip Cargile, both Research Scientists at CfA, and Zihao Wu, a Harvard Ph.D. student at CfA, also played important roles.

"It is stunning that the universe can make such a galaxy in only 300 million years."

Because of the expansion of the universe, the light from distant galaxies stretches to longer wavelengths as it travels. This effect is so extreme for these two galaxies that their ultraviolet light is shifted to infrared wavelengths where only JWST can see it. Because light takes time to travel, more distant galaxies are also seen as they were earlier in time.

The two record-breaking galaxies are called JADES-GS-z14-0 and JADES-GS-z14-1, the former being the more distant of the two. In addition to being the new distance record holder, JADES-GS-z14-0 is remarkable for how big and bright it is.

"The size of the galaxy clearly proves that most of the light is being produced by large numbers of young stars," said Eisenstein, a Harvard professor and chair of the astronomy department, "rather than material falling onto a supermassive black hole in the galaxy's center, which would appear much smaller."

The combination of the extreme brightness and the fact that young stars are fueling this high luminosity makes JADES-GS-z14-0 the most striking evidence yet found for the rapid formation of large, massive galaxies in the early universe.

"JADES-GS-z14-0 now becomes the archetype of this phenomenon," says Dr. Stefano Carniani of the Scuola Normale Superiore in Pisa, lead author on the discovery paper. "It is stunning that the universe can make such a galaxy in only 300 million years."

Evidence for surprisingly vigorous early galaxies appeared even in the first JWST images and has been mounting in the first two years of the mission. This trend runs counter to expectations that most astronomers had before the launch of JWST of theories of galaxy formation.

JADES-GS-z14-0 was a puzzle for the JADES team when they first spotted it over a year ago, as it appears close enough on the sky to a foreground galaxy that the team could not be sure that the two were not neighbors. But in October 2023, the JADES team conducted even deeper imaging—five full days with the JWST Near-Infrared Camera on just one field—and used filters designed to better isolate the earliest galaxies.

"We just couldn't see any plausible way to explain this galaxy as being merely a neighbor of the more nearby galaxy," says Dr. Kevin Hainline, research professor at the University of Arizona.

The galaxy is located in a field where the JWST Mid-Infrared Instrument had conducted an ultra-deep observation. Its brightness at intermediate infrared wavelengths is a sign of emission from hydrogen and even oxygen atoms in the early universe.

"Despite being so young, the galaxy is already hard at work creating the elements familiar to us on Earth," said Zihao Wu, a co-author on a second paper about this finding, led by Jakob Helton, a graduate student at the University of Arizona.

Emboldened, the team then obtained a spectrum of each galaxy, and confirmed their hopes that JADES-GS-z14-0 was indeed a record-breaking galaxy and that the fainter candidate, JADES-GS-z14-1, was nearly as far away.

A third paper led by Brant Robertson, professor at the University of California-Santa Cruz, and Ben Johnson, studies the evolution of this early population of galaxies.

"This amazing object shows that galaxy formation in the early universe is very rapid and intense," said Johnson, "and JWST will allow us to find more of these galaxies, perhaps when the universe was even younger. It is a marvelous opportunity to study how galaxies get started."

Birth of universe's earliest galaxies observed for first time

 

Gas that accumulates and accretes onto a mini galaxy in the process of being built. While this is how galaxies are formed according to theories and computer simulations, it had never actually been witnessed. Credit: NASA

Using the James Webb Space Telescope, University of Copenhagen researchers have become the first to see the formation of three of the earliest galaxies in the universe, more than 13 billion years ago. The sensational discovery contributes important knowledge about the universe and is now published in Science.

For the first time in the history of astronomy, researchers at the Niels Bohr Institute have witnessed the birth of three of the universe's absolute earliest galaxies, somewhere between 13.3 and 13.4 billion years ago.

The discovery was made using the James Webb Space Telescope, which brought these first "live observations" of formative galaxies down to us here on Earth.

Through the telescope, researchers were able to see signals from large amounts of gas that accumulate and accrete onto a mini galaxy in the process of being built. While this is how galaxies are formed according to theories and computer simulations, it had never actually been witnessed.

"You could say that these are the first 'direct' images of galaxy formation that we've ever seen. Whereas the James Webb has previously shown us early galaxies at later stages of evolution, here we witness their very birth, and thus, the construction of the first star systems in the universe," says Assistant Professor Kasper Elm Heintz from the Niels Bohr Institute, who led the new study.

Galaxies born shortly after the Big Bang

The researchers estimate the birth of the three galaxies to have occurred roughly 400–600 million years after the Big Bang, the explosion that began it all. While that sounds like a long time, it corresponds to galaxies forming during the first 3–4% of the universe's 13.8-billion-year overall lifetime.

Shortly after the Big Bang, the universe was an enormous opaque gas of hydrogen atoms—unlike today, where the night sky is speckled with a blanket of well-defined stars.

"During the few hundred million years after the Big Bang, the first stars formed, before stars and gas began to coalesce into galaxies. This is the process that we see the beginning of in our observations," explains Associate Professor Darach Watson.

The birth of galaxies took place at a time in the history of the universe known as the Epoch of Reionization, when the energy and light of some of the first galaxies broke through the mists of hydrogen gas.

It is precisely these large amounts of hydrogen gas that the researchers captured using the James Webb Space Telescope's infrared vision. This is the most distant measurement of the cold, neutral hydrogen gas, which is the building block of the stars and galaxies, discovered by scientific researchers to date.

Adds to the understanding of our origins

The study was conducted by Kasper Elm Heintz, in close collaboration with--among others--research colleagues Darach Watson, Gabriel Brammer and Ph.D. student Simone Vejlgaard from the Cosmic Dawn Center at the University of Copenhagen's Niels Bohr Institute—a center whose stated goal is to investigate and understand the dawn of the universe. This latest result brings them much closer to doing just that.

The research team has already applied for more observation time with the James Webb Space Telescope, with hopes of expanding upon their new result and learning more about the earliest epoch in the formation of galaxies.

"For now, this is about mapping our new observations of galaxies being formed in even greater detail than before. At the same time, we are constantly trying to push the limit of how far out into the universe we can see. So, perhaps we'll reach even further," says Vejlgaard.

According to the researcher, the new knowledge contributes to answering one of humanity's most basic questions.

"One of the most fundamental questions that we humans have always asked is 'Where do we come from?' Here, we piece together a bit more of the answer by shedding light on the moment that some of the universe's first structures were created. It is a process that we'll investigate further, until hopefully, we are able to fit even more pieces of the puzzle together," concludes Associate Professor Brammer.