The James Webb Space Telescope deployed in space. Image credit: NASA Animator
The James Webb Space Telescope (JWST) has discovered the most distant galaxy ever identified, forming about 325 million years after the Big Bang.
Astronomers use a metric called redshift to measure the Earth's distance from objects in the universe. Due to the expansion of the universe, the farther a celestial body is from the earth, the faster it is moving away. This measure is similar to the Doppler effect, in which the wavelength of an object's radiation changes due to the relative motion of the source and observer. The faster the light from the galaxy is traveling, the redder the color will become. By comparing the visible color of a galaxy to its actual color, astronomers can determine the distance from Earth to a galaxy.
In JWST's early observations of galaxies, astronomers could only make approximate estimates of each galaxy's redshift because they did not have detailed data from the spectra of these galaxies. These observations provide clues to galaxies at redshifts of 12 or more, meaning they appear to be 30 million light-years away and may have formed within 400 million years of the Big Bang, but the lack of precise evidence has left many scientists unsure about these galaxies. Found skeptical.
"Proving that these galaxies did exist in the early universe is crucial," Emma Curtis-Lake of the University of Hertfordshire, UK, said in a blog post, "It is likely that the closer galaxies masquerade as very distant galaxies. "
More than 80 astronomers from 10 countries are participating in the JWST Advanced Deep Exogalactic Survey (JADES). Now, researchers have identified four extremely distant galaxies with redshifts ranging from 10.4 to 13.2. That means they formed between 325 million and 450 million years after the Big Bang. The previously confirmed highest redshift record was around 11.
"This is the faintest infrared spectrum ever collected." Stefano Carniani of the Supérieure Normale Supérieure in Pisa, Italy, said that the observations covered a total of 250 faint galaxies, and another set of observations is planned for 2023. The observations are expected to confirm many more such distant galaxies, which will tell scientists about the early days of galaxy formation and how the most distant galaxies differ from those around them.
Curtis-Lake and other researchers presented the new findings on Dec. 12 at the Space Telescope Science Institute (STScI) conference in Baltimore, USA, titled "First Science Results from JWST."
"From these measurements, we can know the intrinsic brightness of the galaxy and calculate how many stars it has."
"Now we can start really looking at how galaxies have come together over time," said co-author Brant Robertson of the University of California, Santa Cruz.
"Without understanding the initial stages of a galaxy's development, it is difficult to understand where it is now. What happens later depends largely on the influence of these early stars," added co-author Sandro Tacchella of the University of Cambridge, UK.
Related paper information: https://arxiv.org/abs/2212.04480
(Original title ""Webb" telescope discovered the most distant galaxy so far")