An international team of astronomers has announced the detection of two of the oldest and most distant known galaxies. The light from both comes from just 300 million years after the Big Bang and could only be observed thanks to the power of the James Webb Space Telescope (JWST).
The galaxies are located in a region near the Hubble Ultra Deep Field, a famous Hubble Space Telescope observation that shows some of the most distant galaxies known at the time. JWST’s larger mirrors and infrared capabilities allowed astronomers to see even further into space.
“These galaxies join a small but growing population of galaxies from the first half billion years of cosmic history where we can really probe stellar populations and the characteristic patterns of chemical elements within them,” said Dr Francesco D’Eugenio of the Kavli Institute for Cosmology. at the University of Cambridge, one of the team behind the discovery, said in a statement.
The results are part of the JWST Advanced Deep Extragalactic Survey (JADES) and are known as JADES-GS-z14-0 and JADES-GS-z14-1, the former being slightly more distant than the latter.
The team was able to perform a spectroscopic survey of the galaxies and break their light into a rainbow. Using this rainbow, scientists were able to determine how far away they were and what chemical elements were present. This is possible because chemical elements interact with light at certain wavelengths.
And that’s not all. The light is red due to the expansion of the universe. This is similar to the Doppler Effect, which changes the pitch of an ambulance siren as a vehicle approaches or recedes. In the case of these galaxies, their light is stretched to extreme wavelengths.
“We see additional emission from hydrogen atoms and possibly oxygen, as is common in star-forming galaxies, but here they are shifted to an unprecedented wavelength,” said Jakob Helton, a graduate student at the University of Arizona and lead author of one of the studies. papers describing the discovery.
JADES-GS-z14-0 is small but mighty compared to the Milky Way. It is 1,600 light-years across and forms stars at a rate 20 times faster than our own silent galaxy. Before JWST, astronomers didn’t expect galaxies to get big, bright, and massive very quickly, but galaxies like this one suggest that this is definitely the way they can grow.
“JADES-GS-z14-0 is now becoming the archetype of this phenomenon,” said Dr. Stefano Carniani of the Scuola Normale Superiore in Pisa, lead author of the discovery. “It’s amazing that the universe can create such a galaxy in just 300 million years.”
JWST is designed to search for the most distant galaxies yet discovered, so expect this current record holder to be superseded relatively soon. These observations suggest that objects significantly closer to the big bang could soon be found.
“We could detect this galaxy even if it was 10 times fainter, which means we could see other examples even earlier in the universe – probably within the first 200 million years,” said Brant Robertson, a professor of astronomy and astrophysics at the university. of California-Santa Cruz and lead author of the third paper on the team’s study of the evolution of these galaxies. “The first universe has so much more to offer.
Documents related to the discovery are awaiting peer review but have been posted to arXiv. Carniani’s paper confirmed the distance, Helton’s paper is about galactic properties, and Robertson’s paper provides insight into how such a galaxy could grow so large in such a short time.