It’s a record that’s been broken multiple times in just the last couple of years, and one that we expect to see broken again soon.
Astronomers using the newly commissioned James Webb Space Telescope (JWST) have announced the discovery of what appears to be the most distant galaxy yet.
If this sounds familiar, it has 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 surprising. Discovered in the darkness of the early Universe, it represents a time just 235 million years after the Big Bang … practically a cosmic twinkle, in the context of the Universe’s 13.8 billion year old age.
The discovery of the galaxy candidate, named CEERS-93316, marks the beginning of something wonderful: Webb is about to open up the early Universe, giving us an unprecedented look at the dark and mysterious achievements at the beginning of, well, everything.
A paper led by astrophysicist Callum Donnan of the University of Edinburgh has been submitted to Monthly Notices of the Royal Astronomical Societyawaiting peer review and is available on the arXiv preprint server.
The first billion years after the Big Bang are of great interest to cosmologists. During this time, the hot, quantum soup that filled the Universe after it blinked into existence somehow began to form everything: matter and antimatter and dark matter, stars and galaxies and dust.
Because light takes time to travel, any light that reaches us from deep space represents an event buried deep in the past; So, in effect, light is a time machine for the far reaches of the Universe. But the early Universe – really early – is more challenging: it’s so far away that any light that reaches us is very, very faint.
In addition, the expansion of the Universe has stretched even the most energetic waves into small wavelengths closer to the infrared parts of the spectrum, making even the most visible objects difficult to read.
This makes detailed reconstructions of that time very difficult. This is even more of a shame, as it is such a critical time.
The era before the birth of the first stars was called the Cosmic Dawn. Beginning nearly 250 million years after the Big Bang, it filled the entire Universe with a dark cloud of hydrogen atoms.
It was only when ultraviolet light from the first stars and galaxies reionized the neutrally charged hydrogen that the entire electromagnetic spectrum could be propagated.
Thanks to this age of reionization, about a 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 merged, how supermassive black holes could form so quickly in their first hundreds of millions of years of existence. Looking into that distant, hazy time is one of the main tasks for which the Webb was designed.
Webb can capture near-infrared and infrared light, with the highest resolution of any telescope ever sent into space. It’s designed to excel at detecting those highly redshifted galaxies, so that cosmologists can finally get a detailed look at what’s going on, if not at the Cosmic Dawn, then at least during Reionization .
CEERS-93316, according to Donnan and his colleagues, should be at least fairly close to one of the first galaxies after the Big Bang. The team ruled out other possible explanations for the faint, red glow, and their analysis suggests that star formation in the galaxy candidate should have begun sometime between 120 and 220 million years after the Big Bang.
However, to confirm the identity of the object, follow-up spectroscopic observations will have to be undertaken. This would hopefully confirm the redshift; from there, the object can become the subject of further, more detailed study and help build a record of early objects in the Universe.
If CEERS-93316 is a galaxy, it probably won’t hold the most distant galaxy ever for long. Even if CEERS-93316 turns out not to be such a distant galaxy, chances are good that it won’t be long before Webb turns up an object that is.
Bring us those pale, red, distant treasures, Webb. We can’t wait.
The research was submitted to Monthly Notices of the Royal Astronomical Societyand is available on arXiv.