These six distant galaxies captured by JWST are thrilling astronomers

This month, researchers unveiled the results of one of the largest and deepest astronomical surveys of the night sky by the James Webb Space Telescope (JWST). The effort has identified some of the first galaxies ever seen in the first 650 million years after the birth of the Universe in the Big Bang. And the findings dazzled astronomers, revealing that stars and galaxies were forming and evolving much earlier than previously suspected.

The project, known as the JWST Advanced Deep Extragalactic Survey (JADES), peered at several patches of sky, including one in the constellation Fornax made famous in 2004 after the Hubble Space Telescope observed it for 11 days, revealing thousands of galaxies. Unlike Hubble, however, JWST operates primarily at infrared wavelengths of light, making it ideal for spotting extremely distant galaxies, whose light is stretched as the Universe expands, making it appear redder.

The starlight from these objects has traveled such great distances that it looks like it did not long after the Big Bang, 13.8 billion years ago. Astronomers measure distance using a factor known as redshift: the higher the redshift, the more distant the object.

Prior to JWST’s 2021 launch, only a few dozen galaxies had been identified with redshifts greater than 8. JADES identified as many as 717 galaxies likely to lie in this range1. Here, astronomers help out Nature make sense of the deluge of data by picking a few of their favorite galaxies (listed from farthest to least) and explaining what the objects can teach us about the early days of the Universe.

The record holder

JADES-GS-z13-0 JWST NIRCam imaging

The record holder.Credit: JADES Collaboration, BE Robertson et al./Nature astronomy

This fuzzy red spot may not sound like much, but it’s the current record holder for the most distant known object in the Universe. JWST discovered the galaxy, known as JADES-GS-z13-0, late last year and then confirmed2, through detailed studies of its starlight, which is at a redshift of 13.2. That means it looks as it did just 320 million years after the Big Bang.

The galaxy is physically small, just a few hundred light-years away, but it’s producing new stars at a rate comparable to today’s Milky Way, says Brant Robertson, an astronomer at the University of California, Santa Cruz. It’s remarkable because scientists had thought that the first galaxies to form in the Universe would slowly merge as stars ignited and merged. JADES-GS-z13-0 and other similar items show3 that the first galaxies were hotbeds of star formation.

These galaxies are the building blocks of the universe, says Kevin Hainline, an astronomer at the University of Arizona in Tucson. With JWST, he adds, we saw them everywhere.

The glowing dog bone

JWST NIRCam images by JADES-GS+53.076-27.807

The glowing dog bone.Credit: JADES Collaboration

Researchers think this dog-bone-shaped object has a redshift of 11.3, though that distance has yet to be confirmed. Assuming it is, then it looks like it was about 400 million years after the Big Bang.

JWST is finding more early structure in the Universe than anyone expected: The Dog Bone appears to be two smaller galaxies in the process of merging. So, 400 million years after the Big Bang, the Universe had already formed stars that clustered into galaxies, and two of those galaxies had merged.

Before JWST began surveying the night sky, scientists hadn’t thought that so much galactic action was possible so early in the Universe. I didn’t expect to see these kinds of objects in our data at all, says Hainline.

The one with (maybe) the first stars

The region around GN-z11.

The one with (maybe) the first stars.Credits: Collaboration GIADA, S. Tacchella et al./arXiv (CC BY 4.0)

With a redshift of 10.6, this galaxy is surprisingly bright just 430 million years after the Big Bang, Robertson says. First identified by Hubble, the galaxy, called GN-z11, appears as an incredibly compact luminous sphere under the gaze of JWST4. That brightness could come from a giant black hole at its center, around which superheated gas and dust spiral.5.

Other JWST observations suggest that this galaxy contains some of the earliest stars to form in the Universe6. The evidence, in the form of chemically unusual pockets of primordial helium gas around the galaxy’s edges, is tentative.

But the very first stars would have been made up mostly of hydrogen and helium, with very few other chemical elements. This is exactly what JWST may have identified in GN-z11. If so, it would fulfill astronomers’ long-held dream of detecting these stars.

The big, lumpy one

JWST NIRCam Imaging by JADES-GS-53.08-27.86

The big, lumpy one.Credit: JADES Collaboration, KN Hainline et al./arXiv (CC BY 4.0)

This bulbous galaxy is at a redshift of 8, placing it about 300 million years after the record holder. Given the lumpy structure it developed, however, those 300 million years must have been action-packed.

If the 13.8 billion year history of the Universe were compressed into a two-hour movie, the first five minutes that set up the plot for everything that follows would show all of the first galaxies JWST is finding, Hainline says. And this massive galaxy, spanning about 3.7 kiloparsecs (12,000 light-years), indicates that the Universe was dynamic from the start.

The reverse one

A red-green-blue (F444W-F410M-F277W) image of the galaxy, where the central core and disk are prominent.

The reverse one.Credit: JADES Collaboration, WM Baker et al./arXiv (CC BY 4.0)

This small galaxy, seen as it was 700 million years after the Big Bang, has more stars forming at its periphery than at its center.

It’s the first time we’ve been able to quantify reverse growth at such an early stage in the Universe, says Sandro Tacchella, an astrophysicist at the University of Cambridge, UK. It’s surprising because the theory suggests the opposite that early galaxies should have stars forming closer to their centers.

This galaxy appears to have started right away, forming as many stars in its compact heart as large galaxies now have7. Subsequently, he devoted himself to the creation of stars in the periphery of him, which is the phase in which astronomers can see him today.

The Cosmic Rose

The JADES NIR Cam "Cosmic Rose"

The Cosmic Rose.Credit: JADES Collaboration, DJ Eisenstein et al./arXiv (CC BY 4.0)

This floral gathering of very dusty, very red galaxies almost immediately caught the attention of the JADES team, earning it the nickname Cosmic Rose.

He has a special place in the heart of the team, says Stacey Alberts, an astronomer at the University of Arizona in Tucson. Scientifically, it’s a beautiful demonstration of the JWST’s leap forward in understanding how red the Universe is.

The rose galaxies are probably not physically related to each other, because they are located at varying distances ranging from 2.5 to 3.9 redshifts. But those values ​​put them at the center of cosmic noon, a period about three billion years after the Big Bang, when galaxies formed stars so rapidly and furiously that they produced most of the stars known in the Universe today.

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Image Source : www.nature.com

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