Cosmic Dawn Revealed: JWST Captures First Direct Image of Formation of Universe's Earliest Galaxies

Using the James Webb Space Telescope, scientists were able to see three of the earliest galaxies in the cosmos. The galaxies were spotted actively forming when the universe was only 400 million to 600 million years old.

Birth of Earliest Galaxies

At Niels Bohr Institute, astronomers have witnessed the birth of three of the absolute earliest galaxies in the cosmos. These galaxies are estimated to have formed somewhere between 13.3 and 13.4 billion years ago.

The discovery was made possible using the James Webb Space Telescope which successfully brought the first 'live observations' of galaxy formation down to us here on Earth. Through JWST, scientists were able to observe signals from large amounts of gas which accumulate into a mini-galaxy.

The formation of galaxies had never actually been witnessed; it was only observed according to theories and computer simulations. It was estimated that the birth of the three galaxies occurred around 400-600 million years after the Big Bang. While it seems like a long time, it corresponds to the formation of galaxies during the first 3-4% of the overall lifetime of the universe.

The formation of the first galaxies in the universe were measured with the use of complex models of the way light was absorbed by the neutral gas located in and around them. This process is known as the Lyman-alpha transition. By measuring the light, the research team was able to distinguish gas from the newly created galaxies from other gas.

What Was the Early Universe Like?

One of the most crucial gaps in our understanding of the history of the cosmos is the "Cosmic Dawn." It refers to the period from around 50 million years to one billion years after the birth of the universe when the first stars, black holes, and galaxies were formed.

It is widely accepted that the universe started 13.8 billion years ago in an enormous explosion known as the Big Bang. This blast gave rise to abundant subatomic particles like quarks and electrons.

The particles then aggregated to form other particles, such as protons and neutrons, which coalesced into atomic nuclei. Shortly after the Big Bang, electrons started to orbit atomic nuclei, which formed the simplest atoms of the universe.

By this time, the cosmos was a large opaque gas made of hydrogen atoms. It was very different from today where we see the night sky teeming with well-defined stars.

The first stars were born after a few hundred million years. At the center of these stars, larger and more complex atoms were created.

In their observations, the researchers saw the process where the first stars formed before they coalesced into galaxies.

The birth of the first galaxies occurred at a time in the history of the cosmos called the Epoch of Reionization. At this point, the energy and light of some of the first galaxies broke through the vapor of hydrogen gas.

It is these enormous amounts of hydrogen gas which were captured by the infrared vision of the James Webb Space Telescope. This is the most distant measurement of the cold, neutral hydrogen gas discovered by scientific researchers to date.