This is a record that has been broken multiple times in the last two years alone, and one that we expect to see broken again soon.
Astronomers using the newly operational James Webb Space Telescope (JWST) have announced the discovery of what appears to be the most distant galaxy yet.
If that sounds familiar, it’s already happened twice this year. In April, astronomers announced their observation of a galaxy at a point in time just 330 million years after the Big Bang. Last month, in other JWST data, another was found at a point 300 million years after the Big Bang.
However, the new record holder is mind-blowing. Discovered in the darkness of the early universe, it represents a time just 235 million years after the Big Bang… practically a cosmic blink, in the context of the universe’s age of 13.8 billion years.
The discovery of the candidate galaxy, called CEERS-93316, marks the beginning of something wonderful: Webb is poised to throw the early Universe wide open, giving us an unprecedented view of the dark and mysterious corners at the beginning of everything.
A paper led by astrophysicist Calum Donnan of the University of Edinburgh is presented at Monthly Notices of the Royal Astronomical Societypending peer review and available on arXiv preprint server.
The first billion years after the Big Bang are of great interest to cosmologists. During that time, the hot, quantum soup that filled the universe after it came into existence somehow began to form everything: matter, antimatter and dark matter, stars and galaxies and dust.
Because light takes time to travel, any light reaching us from deep space represents an event buried deep in the past; so light is effectively a time machine for the far reaches of the universe. But the early universe – the really early one – is more of a challenge: it’s so far away that any light that reaches us is very, very faint.
What’s more, the expansion of the universe has stretched even the most energetic waves into faint rays closer to the infrared parts of the spectrum, making even more visible objects difficult to read.
This makes very detailed reconstructions from that time difficult. Which is all the more unfortunate since it’s such a critical moment.
The era before the birth of the first stars is called the Cosmic Dawn. Beginning nearly 250 million years after the Big Bang, it filled the entire universe with an opaque cloud of hydrogen atoms.
Only when ultraviolet light from the first stars and galaxies reionized the neutrally charged hydrogen could the entire electromagnetic spectrum be propagated.
Thanks to this Age of Reionization, about one billion years after the Big Bang, light can once again shine unhindered.
Naturally, we want to know more about the youth of the universe during this nebulous period; how those first stars formed in the dawn clouds, how galaxies came together, how supermassive black holes could form so quickly in their first hundreds of millions of years of existence. Peering back into that distant, hazy time is one of the primary tasks for which the Webb is designed.
Webb can capture near-infrared and infrared light at the highest resolution of any telescope ever sent into space. It is designed to outperform the detection of these very high-redshift galaxies so that cosmologists can finally see in detail what is happening, if not in the Cosmic Dawn, then at least during Reionization.
CEERS-93316, according to Donnan and his colleagues, must be at least fairly close to one of the first galaxies after the Big Bang. The team ruled out other potential explanations for the faint red glow, and their analysis suggests that star formation in the candidate galaxy must have begun sometime between 120 and 220 million years after the Big Bang.
To confirm the identity of the object, however, follow-up spectroscopic observations will have to be undertaken. Hopefully this will confirm the redshift; from there, the object can become the subject of further, more detailed study and help build a census of objects from the early universe.
If CEERS-93316 is a galaxy, it probably won’t carry the most distant galaxy for a long time. Even if CEERS-93316 doesn’t turn out to be such a distant galaxy, chances are good that we won’t have to wait long for the Webb to find an object that is.
Bring us those dark, red, distant treasures, Webb. I can not wait
The research was submitted to Monthly Notices of the Royal Astronomical Societyand is available on arXiv.