The James Webb Space Telescope (JWST) has discovered some potential galaxies that may be among the oldest known to have ever existed.
Located 13.6 billion light-years away and just 200 million years after the Big Bang, the five galaxy candidates are the oldest galaxies ever discovered, and possibly the first galaxies to form in the ancient universe.
If confirmed by follow-up observations, the ancient galaxies will allow astronomers to test their best theories of galaxy formation, as well as provide unique insights into how matter first accreted in the universe. The researchers published their findings on Nov. 26 on the preprint database arXiv, so they have not yet been peer-reviewed.
“According to the standard paradigm of structure formation, the same primordial fluctuations that gave rise to hot and cold spots in the cosmic microwave background (CMB) would eventually grow, collapse and form the first galaxies during the cosmic dawn, ushering in the era of the first light,” the researchers wrote in their study.
“These first galaxies remained out of our observational reach for decades,” he said. Yet the JWST has changed that. Cosmologists previously estimated that the first clusters of stars began to merge and galaxies to form only a few hundred million years after the Big Bang.
Then, only 1 to 2 billion years into the universe’s life, current theories suggest that these early protogalaxies reached adolescence — turning into dwarf galaxies that swallowed each other and evolved to become something like our own. But the exact timing of this process and the speed at which the early stages occurred are challenging to detect because the light coming from these galaxies is very weak and the expansion of the universe has dramatically stretched (or redshifted) their wavelengths into the infrared spectrum.
Unlike its predecessor, the Hubble Space Telescope, the JWST can detect light in the infrared spectrum, giving the telescope access to the very first stages of the universe. But the light coming from the extremely early epochs of our universe is still too dim to be detected on its own.
To tackle this problem, the researchers behind the new observations, made as part of the Galactic Legacy Infrared Midplane Survey Extraordinaire (GLIMPSE) project, took advantage of a phenomenon called gravitational lensing to magnify the distant light of these early galaxies.
As Einstein outlined in his theory of general relativity, gravity is the curvature and distortion of space-time in the presence of matter and energy. This curved space, in turn, determines how energy and matter move.
This means that even though light travels in a straight line, it can be bent and magnified by gravity. In this case, the galaxy Abell S1063 lies between the region they chose to study and our solar system, focusing the early galaxy’s light so that it can be seen by telescopes.
By pointing the JWST at this region of curved space and slowly collecting the light coming from behind it, astronomers pushed the telescope to the limits of its capabilities, catching the first faint glimpses from early galaxies.
If confirmed by further studies, these galaxy candidates would be about 90 million years younger than the oldest confirmed galaxy, JADES-GS-z14-0 – making them among the earliest galaxies to form. And the fact that they were all found in the same region of the sky suggests there may be many more of them out there.
So how did galaxies like these grow so quickly? Answers to the cosmic mystery are still elusive, but it’s unlikely that they will shatter our current understanding of cosmology. Instead, astronomers are toying with explanations that include the appearance of giant black holes already forming, feedback from supernova explosions or even the influence of dark energy, which explains the rapid formation of stars within them.