James Webb Space Telescope spies most ancient galaxies ever observed

The potent satellite observatory observed four galaxies as recently as 350 million years after the Big Bang.

The oldest galaxies ever seen have been seen by the James Webb Space Telescope (JWST).

According to two recent studies, astronomers can now be sure that the light from these galaxies has been moving to Earth for more than 13.4 billion years. The findings illustrate the quick emergence of the first generations of galaxies and reveal that these galaxies lived in the cosmos when it was only 350 million years old.

The need to demonstrate that these galaxies do, in fact, live in the early cosmos was critical. According to Emma Curtis-Lake, an astrophysicist at the University of Hertfordshire in England and a co-author of one of the new investigations, "it's very feasible for closer galaxies to pose as very faraway galaxies.

"Seeing the spectrum exposed as we had anticipated, it confirmed that these galaxies are at the true edge of our field of vision, some of which are farther away than Hubble could see! It is an incredibly thrilling accomplishment for the cause, according to Curtis-Lake.

The finding supports JWST's capacity to carry out one of its most crucial jobs, namely investigating the early universe using light whose wavelength has been stretched by the universe's expansion due to how far it has traveled. Redshift refers to the lengthening of light; the further toward the red end of the electromagnetic spectrum the light is shifted by the universe's growth. As a result, redshift can be used to calculate distance, and early galaxies should have light that exhibits severe redshifts and is stretched all the way into the infrared, which is a speciality of the JWST.

The $10 billion telescope has so far discovered a number of exceptionally high-redshift candidate galaxies, but spectroscopy still needs to be used to verify these findings.

Because spectroscopy can identify the distinctive signatures of particular elements, it can be used to distinguish between distant, more recent galaxies that might share comparable characteristics and early galaxies. Early planets lack stronger elements like oxygen, nitrogen, and carbon and are primarily made of hydrogen and helium. This is due to the fact that they have not yet been enriched by the heavier elements that stars produce through nuclear fusion and then spread when they supernova and expire.

The four galaxies designated JADES-GS-z10-0, JADES-GS-z11-0, JADES-GS-z12-0, and JADES-GS-z13-0 do in fact have extreme redshifts, ranging from 10.3 to 13.2, according to the researchers' analysis of data obtained from JWST's near-infrared camera (NIRCam) and Near-Infrared Spectrograph (NIRSpec) instrument. (JADES, by the way, stands for "JWST Advanced Deep Extragalactic Survey.")

This result was reached because these galaxies' spectra lack the distinctive trace of heavy elements like carbon, indicating that JWST is viewing them as they were when the universe was only 300–500 million years old. (The universe is currently about 13.8 billion years old.)

Brant Robertson, a co-author and part of the NIRCam scientific team, said in the statement, "For the first time, we have found galaxies only 350 million years after the Big Bang, and we can be completely sure of their amazing distances. It is a unique experience to discover these early galaxies in such exquisitely gorgeous pictures.

The data originate from the first round of JADES studies, which focused on the Ultra Deep Field, a small region of the sky that has been studied for about 20 years by the Hubble Space Telescope. Around 100,000 galaxies can be found in this area of the heavens, each captured at a specific time in its existence, possibly billions of years ago.

The Ultra Deep Field was studied with NIRCam over the course of more than ten days of the JWST mission, with observations made in nine distinct infrared wavelengths. The NIRSpec device then collected data for 28 hours over the course of three days. JWST thus provided scientists with the information they required to precisely measure each galaxy's redshift and disclose the characteristics of the gas and stars within each one, as well as delivering extremely sensitive and clear pictures of the area.

According to Marcia Rieke, the primary scientist for NIRCam at the University of Arizona, "These results are the culmination of why the NIRCam and NIRSpec teams joined together to execute this observing program."

The two papers were published today (April 4) in the journal Nature(opens in new tab). The researchers first reported the results in December 2022, when they presented them at a conference.