After many hours of staring unblinking at a small patch of sky, JWST has given us the most detailed map ever obtained of a corner of the Universe.
It’s called the COSMOS-Web field, and if that sounds familiar, it’s probably because an incredible image of it dropped just a month ago. That, however, was just a little taste of what has now come to pass.
The full, interactive map and all the data have just dropped, a map that vastly outstrips the famous Hubble Ultra Deep Field’s 10,000 galaxies. The new map contains nearly 800,000 galaxies – hopefully heralding in a new era of discovery in the deepest recesses of the Universe.
“Our goal was to construct this deep field of space on a physical scale that far exceeded anything that had been done before,” says physicist Caitlin Casey of the University of California Santa Barbara, who co-leads the COSMOS collaboration with Jeyhan Kartaltepe of the Rochester Institute of Technology.
“If you had a printout of the Hubble Ultra Deep Field on a standard piece of paper, our image would be slightly larger than a 13-foot by 13-foot-wide mural, at the same depth. So it’s really strikingly large.”
JWST is our best hope for understanding the Cosmic Dawn, the first billion or so years after the Big Bang, which took place around 13.8 billion years ago. This epoch of the Universe is extremely difficult to observe: it’s very far away, and very faint. Because the Universe is expanding, the light that travels to us from greater distances is stretched into redder wavelengths.
With its powerful resolution and infrared capabilities, JWST was designed for just these observations: finding the faint light from the dawn of time which informs us on the processes that gave rise to the Universe we see around us today.
The COSMOS-Web image covers a patch of sky a little bigger than the area of 7.5 full Moons, and peers back as far as 13.5 billion years, right into the time when the opaque primordial fog that suffused the early Universe was beginning to clear.
There, the researchers are looking not just for early galaxies, they’re looking for an entire cosmic ecosystem – an interactive gravitational dance of objects bound by the cosmic web of dark matter that spans the entire Universe.
JWST data collected to date indicates that even with Hubble data, we’ve barely scratched the surface of what lurks within the Cosmic Dawn.
“The Big Bang happens and things take time to gravitationally collapse and form, and for stars to turn on. There’s a timescale associated with that,” Casey says.
“And the big surprise is that with JWST, we see roughly ten times more galaxies than expected at these incredible distances. We’re also seeing supermassive black holes that are not even visible with Hubble.”
This profusion of well-formed galaxies hasn’t just surprised astronomers – it’s given them a whopping great puzzle to solve. According to our current understanding of galaxy evolution, not enough time had elapsed since the Big Bang for them to have formed.
Even one is a bit of a head-scratcher – but the numbers in which JWST is finding them just boggle the mind. With access to datasets free and available to everyone who wants to take a crack, however, we may get a few answers.
“A big part of this project is the democratization of science and making tools and data from the best telescopes accessible to the broader community,” Casey says.
“The best science is really done when everyone thinks about the same data set differently. It’s not just for one group of people to figure out the mysteries.”
Papers on the data have been submitted to the Astrophysical Journal and Astronomy & Astrophysics. Meanwhile, you can head over to the COSMOS-Web interactive website and muck about zooming through the Universe nearly all the way back to the beginning of time.
