An international team of astronomers has announced the discovery of two of the earliest and most distant known galaxies. The light from both comes just 300 million years after the Big Bang and was only possible to observe thanks to the power of the James Webb Space Telescope (JWST).
The galaxies are located in an area 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 deeper 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 the stellar populations and the characteristic patterns of chemical elements within them,» Dr Francesco D’Eugenio of the Kavli Institute for Cosmology at the University of Cambridge, one of the team behind the discovery, he 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 conduct a spectroscopic survey of the galaxies, decomposing their light into a rainbow. Using this rainbow, researchers 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. Due to the expansion of the universe, light is redshifted. This is similar to the Doppler effect, which changes the pitch of an ambulance’s siren as the vehicle approaches or recedes. In the case of these galaxies, their light is stretched to extreme wavelengths.
«We see additional emission from hydrogen and perhaps even oxygen atoms, as is common in star-forming galaxies, but here it has shifted to an unprecedented wavelength,» said Jakob Helton, a graduate student at the University of Arizona and lead author of a papers detailing the discovery.
JADES-GS-z14-0 is small compared to the Milky Way, but powerful. It is 1,600 light-years across and forms stars 20 times faster than our quiescent 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 paper. «It’s amazing that the Universe can make such a galaxy in just 300 million years.»
JWST was designed to search for the most distant galaxies ever discovered, so expect this current record-holder to be superseded relatively soon. These observations suggest that objects much closer to the Big Bang may soon be found.
«We could have detected this galaxy even if it was 10 times fainter, which means we could see other examples even earlier in the universe — probably in 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 early universe has much more to offer.»
Papers related to the discovery are awaiting peer review, but have been published on arXiv. Carniani’s work confirmed the distance, Helton’s work deals with galactic properties, and Robertson’s work provides insight into how such a galaxy managed to grow so large in such a short time.