The James Webb Space Telescope (JWST) has clapped eyes on the most ancient galaxies ever observed.
Astronomers are now confident that the light from these galaxies has been traveling to Earth for over 13.4 billion years, two new studies report. The results show that these galaxies inhabited the universe when it was less than 350 million years old and demonstrate the rapid emergence of the first generations of galaxies.
"It was crucial to prove that these galaxies do, indeed, inhabit the early universe. It's very possible for closer galaxies to masquerade as very distant galaxies," Emma Curtis-Lake, a co-author of one of the new studies and an astronomer at the University of Hertfordshire in England, said in a statement.
"Seeing the spectrum revealed as we hoped, confirming these galaxies as being at the true edge of our view, some further away than Hubble could see! It is a tremendously exciting achievement for the mission," Curtis-Lake said.
Related: James Webb Space Telescope: Everything you need to know
The discovery confirms JWST's ability to perform one of its most important tasks — studying the early universe via light that has been traveling for so long that the expansion of the universe has stretched its wavelength. This stretching of light is called redshift; the longer the light travels, the further toward the red end of the electromagnetic spectrum the expansion of the universe shifts its light. This means that redshift can be used as a measure of distance, and that early galaxies should have light displaying extreme redshifts, with their light stretched all the way into the infrared range — JWST's specialty.
Thus far, the $10 billion observatory has identified several extremely high-redshift candidate galaxies, but these observations have to be confirmed using spectroscopy.
Spectroscopy can be used to make the distinction between early galaxies and closer, more contemporary galaxies that might share similar properties, because spectroscopy can spot the characteristic fingerprints of specific elements. Early galaxies are composed of mostly hydrogen and helium, lacking heavier elements like oxygen, nitrogen and carbon. This is because they have not yet been enriched by the heavy elements forged by stars via nuclear fusion and then dispersed when these stars die and go supernova.
The researchers' analysis of data collected from JWST's near-infrared camera (NIRCam) and Near-Infrared Spectrograph (NIRSpec) instrument allowed them to determine that the four galaxies designated JADES-GS-z10–0, JADES-GS-z11–0, JADES-GS-z12–0, and JADES-GS-z13–0 do indeed have extreme redshifts, of 10.3 to 13.2. (JADES, by the way, stands for "JWST Advanced Deep Extragalactic Survey.")
They came to this conclusion because the spectra from these galaxies lack the telltale signature of heavy elements like carbon, meaning JWST is seeing them as they were when the universe was just 300 to 500 million years old. (The universe is currently about 13.8 billion years old.)
"For the first time, we have discovered galaxies only 350 million years after the Big Bang, and we can be absolutely confident of their fantastic distances," co-author and NIRCam science team member Brant Robertson said in the statement. "To find these early galaxies in such stunningly beautiful images is a special experience."
The observations come from the first round of JADES observations, which were directed toward a tiny area of the sky known as the Ultra Deep Field that has been investigated for around two decades by the Hubble Space Telescope. This patch of sky contains around 100,000 galaxies, each caught at some moment in its history, potentially billions of years in the past.
The researchers used over 10 days of JWST mission time to study the Ultra Deep Field with NIRCam, observing it in nine different infrared colors. This was followed by 28 hours of data collection conducted by the NIRSpec instrument over three days. JWST therefore delivered exceptionally sensitive and sharp images of the region and also provided astronomers the data they needed to get a precise measurement of each galaxy's redshift and reveal the properties of the gas and stars within each one.
"These results are the culmination of why the NIRCam and NIRSpec teams joined together to execute this observing program," said NIRCam principal investigator Marcia Rieke of the University of Arizona.
The two papers were published today (April 4) in the journal Nature. The researchers first reported the results in December 2022, when they presented them at a conference.
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There is no stretching - the wavelength of light is invariable. Frequency and speed vary proportionally, in accordance with the formula
(frequency) = (speed of light)/(wavelength)
If light can slow down in vacuum, then we have a static-universe explanation of both the cosmological (Hubble) redshift and Halton Arp's intrinsic redshift. The idea of slow speed of light in vacuum is not too preposterous:
"Some physicists, however, suggest that there might be one other cosmic factor that could influence the speed of light: quantum vacuum fluctuation. This theory holds that so-called empty spaces in the Universe aren't actually empty - they're teeming with particles that are just constantly changing from existent to non-existent states. Quantum fluctuations, therefore, could slow down the speed of light." https://www.sciencealert.com/how-much-do-we-really-know-about-the-speed-of-light
Can light slow down in vacuum? Yes:
"The speed of light is a limit, not a constant - that's what researchers in Glasgow, Scotland, say. A group of them just proved that light can be slowed down, permanently..."But once that pattern has been imposed - even now the light is no longer in the mask, it's just propagating in free space - the speed is still slow," Padgett added." http://www.upi.com/Science_News/2015/01/23/Scientists-slow-down-light-particles/1191422035480
"Glasgow researchers slow the speed of light" x2ffsymView: https://www.dailymotion.com/video/x2ffsym
"Researchers at the University of Ottawa observed that twisted light in a vacuum travels slower than the universal physical constant established as the speed of light by Einstein’s theory of relativity...If it’s possible to slow the speed of light by altering its structure, it may also be possible to speed up light. The researchers are now planning to use FROG to measure other types of structured light that their calculations have predicted may travel around 1 femtosecond faster than the speed of light in a vacuum." https://www.optica.org/en-us/about/newsroom/news_releases/2016/slowing_down_light_with_a_twist/
My observation. The report does not show they found gas that is zero-metals. Did JWST see pristine gas clouds from BBN then? I did not see this in the report. I note from the paper cited: "In the Methods, the stellar and gas-phase metallicities are shown to be poorly constrained but consistent with being under a tenth of the solar value, and the visual dust attenuation in these galaxies is AV ≲ 0.3 mag, with large uncertainty. The integrated yield of a previous Type II supernovae is enough to enrich these galaxies with metals provided at least roughly 10% of ejected metals remain and that the SFH has been sustained longer than 10 Myr (ref. 46)."
My observation, apparently no zero-metal gas clouds are seen here by JWST. The abstract states: "Surveys with the James Webb Space Telescope ( JWST) have discovered candidate galaxies in the first 400 Myr of cosmic time. Preliminary indications have suggested these candidate galaxies may be more massive and abundant than previously thought. However, without confirmed distances, their inferred properties remain uncertain. Here we identify four galaxies located in the JWST Advanced Deep Extragalactic Survey Near-Infrared Camera imaging with photometric redshifts z of roughly 10–13. These galaxies include the first redshift z > 12 systems discovered with distances spectroscopically confirmed by JWST in a companion paper. Using stellar population modelling, we find the galaxies typically contain 100 million solar masses in stars, in stellar populations that are less than 100 million years old. The moderate star-formation rates and compact sizes suggest elevated star-formation rate surface densities, a key indicator of their formation pathways. Taken together, these measurements show that the first galaxies contributing to cosmic reionization formed rapidly and with intense internal radiation fields."
There are words of caution like *poorly constrained* and *their inferred properties remain uncertain*.
Using cosmology calculators, z=13.2, the comoving radial distance = 33.386 Gly away from Earth today. There is no way to know if this galaxy continued to evolve as BB cosmology interprets based upon using look back time distances for others. At the comoving radial distance, space is expanding ~ 2.36 c velocity. There seems to be a very number of parameters/assumptions used to explain what is seen by JWST with redshifts in the range of 10-13 or so.