The James Webb Space Telescope has observed the most distant galaxy ever seen, named JADES-GS-z14-0, a galaxy that exists just 290 million years after the Big Bang.
The observations are part of a study using Webb to explore the Cosmic Dawn: the period when the first stars and galaxies were formed after the birth of the Universe.
The Universe is 13.8 billion years old, but because light takes time to travel across space, by peering deep into the cosmos, astronomers can effectively look back in time.
The deeper astronomers look into the distant Universe, the further back they can see.
What's more, the light that's making its way to our telescopes, travelling millions and billions of lightyears across the Universe, is stretched by the expansion of the Universe.
This stretching is known as 'redshift' because the light is stretched to the red end of the spectrum, and this is why Webb - with its infrared vision - is so good at detecting very early galaxies.
How JADES-GS-z14-0 was found
In October 2023 and January 2024, a team of astronomers used the James Webb Space Telescope to observe galaxies as part of the JWST Advanced Deep Extragalactic Survey (JADES) programme.
Webb’s NIRSpec (Near-Infrared Spectrograph) instrument detected the record-breaking galaxy, known as JADES-GS-z14-0.
JADES-GS-z14-0 appears to us as it existed just 290 million years after the Big Bang, when the Universe was in its infancy.
This amounts to a redshift of about 14, the measure of how much the galaxy’s light has been stretched by the expansion of the Universe.
The authors of the study are Stefano Carniani of Scuola Normale Superiore in Italy and Kevin Hainline, an associate research professor at the Steward Observatory, University of Arizona.
"From the images, the source is found to be over 1,600-light years across, proving that the light we see is coming mostly from young stars and not from emission near a growing supermassive black hole," they say in a joint statement.
"This much starlight implies that the galaxy is several hundreds of millions of times the mass of the Sun. This raises the question: How can nature make such a bright, massive, and large galaxy in less than 300 million years?
"JADES researcher Jake Helton of Steward Observatory and the University of Arizona also identified that JADES-GS-z14-0 was detected at longer wavelengths with Webb’s MIRI (Mid-Infrared Instrument), a remarkable achievement considering its distance.
"The MIRI observation covers wavelengths of light that were emitted in the visible-light range, which are redshifted out of reach for Webb’s near-infrared instruments.
"Jake’s analysis indicates that the brightness of the source implied by the MIRI observation is above what would be extrapolated from the measurements by the other Webb instruments, indicating the presence of strong ionised gas emission in the galaxy in the form of bright emission lines from hydrogen and oxygen.
"The presence of oxygen so early in the life of this galaxy is a surprise and suggests that multiple generations of very massive stars had already lived their lives before we observed the galaxy.
"All of these observations, together, tell us that JADES-GS-z14-0 is not like the types of galaxies that have been predicted by theoretical models and computer simulations to exist in the very early Universe."
Read the full paper at arxiv.org/abs/2405.18485.
