NASA built the cutting-edge James Webb Space Telescope to stare into the distant Universe
and back to the beginning of time — and it's already doing it spectacularly.
In the weeks after Webb's initial science images and data were made available to astronomers,
they have reported a flood of early discoveries, including multiple contenders for the most
distant galaxy ever seen.
The presence of distant galaxies in Webb photos suggests that we should reconsider star and
galaxy evolution in the early universe.
So, keep your eyes glued to your screens because things are about to become interesting.
The first James Webb Space Telescope results appear to imply that massive, dazzling galaxies
formed within the first 250 million years after the Big Bang.
If confirmed, this would seriously challenge current cosmological thinking.
For the time being, though, that remains a significant "if."
Shortly after NASA released Webb's first batch of scientific data, the astronomical preprint
server arXiv (pronounced "archive") was overwhelmed with papers claiming the discovery of galaxies
so distant that their light took 13.5 billion years to reach us.
Many of these appear to be more massive than the mainstream cosmological model, which defines
the composition and evolution of the universe.
“It worries me slightly that we find these monsters in the first few images,” says
cosmologist Richard Ellis (University College London).
It was just last month that the James Webb Space Telescope zeroed in on the "oldest galaxy"
ever seen.
Now a handful are vying for the crown.
Does anybody remember GLASS-z13?
No?
It was spotted by the James Webb Space Telescope and championed as the "oldest galaxy ever
seen" and it was announced...
Last month.
Yes, that's right.
Not even a month ago, two preprint papers posted to scientific article repository arXiv
detailed some of the earliest analysis of images snapped by the JWST, humanity's next-generation
infrared eye on the cosmos.
Lurking within the data were two galaxies -- potentially the most distant galaxies humans
had ever laid eyes on.
One of them was dubbed GLASSz-13 or GL-z13 for short.
"JWST has found the oldest galaxy we have ever seen in the universe" one headline read.
The story exploded across the web, with Twitter buzzing about it and mainstream outlets picking
up on the record-breaking find.
In the rush of reporting, a few key points were missed.
It's not the "oldest galaxy" we've ever seen.
It's maybe the oldest light we've ever detected but it's probably a very young galaxy, no
more than a 100 billion years into its life (an important distinction).
It's also important to note GL-z13 is currently just a "candidate" that requires further investigation
-- the data is pretty good, according to astronomers -- but further observations would help tick
it off as the record holder.
But all that might not even matter.
Astronomers have identified galaxies that may be even further away than GL-z13 in a
flurry of new papers published on arXiv later.
It's a showcase of the power of the revolutionary James Webb Space Telescope.
As soon as researchers were given access to Webb's first batch of data, they began scouring
it for distant galaxies.
Webb is the best at finding these galaxies because it sees the cosmos in infrared light,
rather than visible light like the Hubble Space Telescope does.
Light has a finite speed, so the farther it has traveled to reach us, the further back
in time it originated.
Visible light from the very earliest galaxies in the universe has been "redshifted."
Because the universe has been expanding since the Big Bang, wavelengths of light get stretched
out.
When you stretch the light we can see with our eyes, that stretching shifts it toward
a redder wavelength.
In this case, infrared.
Webb is designed specifically to capture this light.
The letter z is used by astronomers to represent redshift.
Higher z values signify a further look back in time.
For example, z = 1 corresponds to around 7.7 billion years ago, whereas z = 10 corresponds
to approximately 13.2 billion years ago.
At least three papers on arXiv have offered candidate galaxies with z values greater than
16.
This would be approximately 13.6 billion years ago.
The researchers, who outlined their findings in a paper posted July 26 presents a case
for a galaxy at z = 16.7, which would correspond to about 235 million years after the Big Bang.
Using the James Webb Space Telescope, they think this may be the farthest galaxy ever
seen — a distant red smudge 35 billion light-years away.
The galaxy, designated CEERS-93316, was captured as it was just 235 million years after the
Big Bang, using Webb's Near Infrared Camera, which can see back to the very first stars'
flickering.
The new discovery, which is still preliminary and must be confirmed by analyzing the spectra
of the galaxy's light, has already beaten a previous provisional record set by the telescope
when another team discovered GLASS-z13, a galaxy that formed 300 million years after
the Big Bang.
During the six months following Webb's launch, NASA engineers calibrated the telescope's
instruments and mirror segments in preparation for snapping the first images.
Their work was temporarily halted when the telescope was unexpectedly hit by a micrometeoroid
between May 23 and May 25.
The impact caused "uncorrectable" damage to a tiny segment of the telescope's mirror,
but this does not appear to have hampered the telescope's performance.
Since the telescope's spectacular first images were revealed on July 12, shots of fascinating
distant objects have been filling the net.
The newly described record-breaking image was obtained during the telescope's Cosmic
Evolution Early Release Science Survey (CEERS), a deep- and wide-field sky survey.
Surprisingly, the researchers that discovered the image were not even looking for the farthest
distant galaxy ever recorded.
Instead, scientists were compiling a list of 55 early galaxies (44 of which had previously
been detected) to explore how luminous they were at various times after the Big Bang – a
measure that will provide vital insight into the evolution of the young universe.
It takes careful spectroscopic measurements – either by Webb’s spectrometers or by
the ground-based ALMA observatory that operates at even longer wavelengths – to precisely
determine the redshifts, which tells you how far out into space — and thus how far back
in time — you’re looking.
To confirm that the galaxy is as old as its redshift suggests, astronomers will use spectroscopy
to examine the magnitude of light over a range of wavelengths for all of the galaxies discovered
so far by Webb's Near Infrared Spectrograph instrument.
This device employs tiny, 0.1 millimeter-long, 0.2-millimeter-wide movable mirrors that only
let in light from target galaxies while filtering out background radiation, allowing astronomers
to categorize stars in a galaxy by color.
This study will reveal not just the age of the light from galaxies, but also their chemical
composition, size, and temperatures.
Given Webb's incredible rate of discovery, as well as its ability to look as far back
as 100 million years after the Big Bang, it is very unlikely that this is the farthest
galaxy we'll ever observe.
The telescope will probably break its own records a lot more in the coming months — and
we can't wait to see more.
Webb’s distant galaxies are also turning out to have more structure than astronomers
had expected.
One analysis of Webb's first deep-field image discovered an unexpectedly large number of
distant disk-shaped galaxies.
Using Hubble, astronomers discovered that distant galaxies are more irregularly shaped
than nearby galaxies, which, like the Milky Way, have uniform shapes like discs.
According to the theory, early galaxies were more frequently warped by interactions with
adjacent galaxies.
The Webb data, on the other hand, show that there are up to ten times as many distant
disk-shaped galaxies as previously thought.
“With the resolution of James Webb, we are able to see that galaxies have disks way earlier
than we thought they did,” says Allison Kirkpatrick, an astronomer at the University
of Kansas in Lawrence.
That’s a problem, she says, because it contradicts earlier theories of galaxy evolution.
“We’re going to have to figure that out.”
Another preprint manuscript claims that huge galaxies formed earlier in the history of
the Universe than previously thought.
A team lead by Ivo Labbe of Swinburne University of Technology in Melbourne, Australia, reports
finding seven large galaxies with redshifts ranging from 7 to 10.
“We infer that the central regions of at least some massive galaxies were already largely
in place 500 million years after the Big Bang, and that massive galaxy formation began extremely
early in the history of the Universe.”
The surprises from Webb continue even a little later in the Universe’s evolution.
One study looked at Webb's findings of 'cosmic noon,' which occurred about three billion
years after the Big Bang.
This is when star formation peaked in the Universe and the majority of light was created.
Wren Suess, an astronomer at the University of California, Santa Cruz, examined Hubble
and Webb images of galaxies at cosmic noon.
Most of the big galaxies seemed substantially smaller in Webb's infrared wavelengths than
they did in Hubble images.
“It potentially changes our whole view of how galaxy sizes evolve over time,” Suess
says.
Hubble studies suggested that galaxies start out small and grow bigger over time, but the
Webb discoveries suggest that Hubble did not have the complete picture, and that galactic
evolution may be more complex than astronomers thought.
“Right now, I find myself lying awake at three in the morning,” Kirkpatrick says,
“wondering if everything I’ve ever done is wrong.”
Astronomers expect a lot of changes with Webb only getting started on a planned 20-plus
year mission.
And yes, the Webb Space Telescope is on track to provide even more contenders for the farthest
distant galaxy ever observed beyond today.
In fact, astrophysicists are already discovering that the early cosmos may be far busier than
they expected.
Stars may have started forming at a much faster rate than some models have predicted.
How did matter come together and form these galaxies so early on?
We do not yet know.
However, Webb appears to be rewriting what we thought we knew about the beginning of,
well, everything.
It is a cosmic revolution.
So, buckle up.
It's going to be one hell of a ride.
What are your thoughts on whether JWST will discover further distant galaxies?
Will it prove that everything we thought we understood about the universe was wrong?
Let us know in the comments.