The James Webb Space Telescope (JWST) has set eyes on the oldest galaxies ever observed.
Astronomers are now confident that the light from these galaxies It has been traveling to Earth more than 13.4 billion years ago, two new studies report. The results show that these galaxies are inhabited Universe When it was less than 350 million years old, it indicates the rapid emergence of the first generations of galaxies.
“It was very important to prove that these galaxies did indeed live in the early universe. It’s very possible that even closer galaxies disguised themselves as very distant galaxies,” Emma Curtis Lake, co-author on one of the new studies and an astronomer at the University of Hertfordshire in England, said in a paper. statement (Opens in a new tab).
“Seeing the spectrum unfolded as we had hoped, confirming that these galaxies are at the true edge of our view, and some are farther out than Hubble i can see! “It’s a very exciting accomplishment of the mission,” Curtis Lake said.
Related: James Webb Space Telescope: Everything you need to know
The discovery underscores the JWST’s ability to perform one of its most important tasks – studying the early universe through light that was traveling for so long that the expansion of the universe extended its wavelength. This expansion of light is called redshift; The longer the light travels, the more the universe expands toward the red end of the electromagnetic spectrum. This means that the redshift can be used as a measure of distance, and that early galaxies must have had light that displayed extreme redshift, with their light extending into the infrared range—the specialty of JWST.
To date, the $10 billion observatory has identified several candidate galaxies with extremely high redshift, but these observations must be confirmed using spectroscopy.
Spectroscopy can be used to distinguish between early galaxies and closer, more recent galaxies that may share similar characteristics, because spectroscopy can identify distinctive fingerprints of certain elements. Early galaxies consisted mostly of hydrogen and helium, and lacked heavier elements such as oxygen, nitrogen and carbon. This is because they are not yet enriched with the heavy elements that formed it stars by nuclear fusion and then dispersed as these stars die and go Supernova.
The researchers’ analysis of data collected from the JWST Near Infrared Camera (NIRCam) and the Near Infrared Spectroradiometer (NIRSpec) instrument allowed them to determine that the four galaxies designated JADES-GS-z10–0, JADES-GS-z11–0, have JADES- GS-z12–0 and JADES-GS-z13–0 have really intense redshifts, from 10.3 to 13.2. (JADES, by the way, stands for “JWST Advanced Deep Extragalactic Survey.”)
They came to this conclusion because the spectra of these galaxies lack the clear signature of heavy elements such as carbon, which means that the JWST sees them as they were when the universe was only 300 to 500 million years old. (The universe is currently about 13.8 billion years old.)
“For the first time, we’ve detected galaxies just 350 million years after the Big Bang, and we can be pretty confident of their remarkable distances,” Brant Robertson, co-author and NIRCam science team member, said in the release. “Finding these early galaxies in such stunningly beautiful images is a special experience.”
The observations come from the first round of JADES observations, which were pointed at a small region of the sky known as the Ultra Deep Field that has been investigated for nearly two decades by the Hubble Space Telescope. This patch of sky contains about 100,000 galaxies, each of which was discovered at some point in its history, possibly billions of years in the past.
The researchers used more than 10 days of JWST mission time to study the ultra-deep field with NIRCam, observing it in nine different colors of infrared. This was followed by 28 hours of data collection conducted by the NIRSpec instrument over a period of three days. Therefore, JWST has provided exceptionally sensitive and sharp images of the region, and has also provided astronomers with the data they need to obtain an accurate measure of the redshift of each galaxy and reveal the properties of the gas and stars within each one.
“These results are the culmination of why the NIRCam team and NIRSpec have come together to implement this monitoring program,” said Marcia Rieke, NIRCam’s principal investigator from the University of Arizona.
The two papers were published today (4 April) in Nature magazine (Opens in a new tab). The researchers first announced the results in December 2022, when they presented them at a conference.
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