The birth of the universe’s earliest galaxies was observed for the first time

Using the James Webb Space Telescope, researchers at the University of Copenhagen have become the first to see the formation of three of the earliest galaxies in the universe, more than 13 billion years ago. The sensational discovery contributes important insights into the universe and has now been published in the science.

For the first time in the history of astronomy, researchers at the Niels Bohr Institute have witnessed the birth of three of the universe’s absolute earliest galaxies, sometime between 13.3 and 13.4 billion years ago.

The discovery was made using the James Webb Space Telescope, which brought these first “direct observations” of forming galaxies to us here on Earth.

Through the telescope, the researchers were able to see signals from the large amounts of gas that accumulate and pile up into a mini-galaxy in the process of being built. While this is how galaxies form according to theories and computer simulations, it had never been seen before.

“You could say that these are the first ‘live’ images of galaxy formation that we’ve ever seen. While James Webb has previously shown us early galaxies in their later stages of evolution, here we witness their birth itself, and thus, building the first star systems in the universe,” says Assistant Professor Kasper Elm Heintz from the Niels Bohr Institute, who led the new study.

Galaxies born immediately after the Big Bang

Researchers estimate that the birth of the three galaxies occurred roughly 400,600 million years after the Big Bang, the explosion that started it all. While this sounds like a long time, it corresponds to galaxies forming during the first 34% of the universe’s overall 13.8 billion-year lifetime.

Immediately after the Big Bang, the universe was an opaque gas of hydrogen atoms, unlike today, where the night sky is speckled with a blanket of well-defined stars.

“During the few hundred million years after the Big Bang, the first stars formed, before stars and gas began to coalesce into galaxies. This is the process that we see the beginning of which we see in our observations,” explains Associate Professor Darach Watson .

The birth of galaxies occurred at a time in the history of the universe known as the Reionization Era, when the energy and light of some of the first galaxies penetrated through clouds of hydrogen gas.

It is precisely these large amounts of hydrogen gas that researchers captured using the infrared vision of the James Webb Space Telescope. This is the most distant measurement of cold neutral hydrogen gas, which is the building block of stars and galaxies, discovered by scientific researchers to date.

It adds to the understanding of our origins

The study was conducted by Kasper Elm Heintz, in close collaboration with – among others – research colleagues Darach Watson, Gabriel Brammer and Ph.D. student Simone Vejlgaard from the Cosmic Dawn Center at the University of Copenhagen’s Niels Bohr Center, whose stated goal is to investigate and understand the dawn of the universe. This latest result brings them that much closer to doing just that.

The research team has already applied for more observing time with the James Webb Space Telescope, hoping to expand on their new result and learn more about the earliest era in galaxy formation.

“At the moment, it’s about mapping out our new observations of galaxies that have formed in even greater detail than before. At the same time, we’re constantly trying to push the limit of how far we can see into the universe So, maybe we’ll go even further,” says Vejlgaard.

According to the researcher, the new knowledge contributes to the answer to one of the most basic questions of humanity.

“One of the most basic questions we humans have always asked is ‘Where do we come from?’ Here, we piece together a little more of the answer by shedding light on when some of the universe’s first structures were created. together”, concludes Associate Professor Brammer.

The study was conducted by researchers Kasper E. Heintz, Darach Watson, Gabriel Brammer, Simone Vejlgaard, Anne Hutter, Victoria B. Strait, Jorryt Matthee, Pascal A. Oesch, Pall Jakobsson, Nial R. Tanvir, Peter Laursen, Rohan P. Naidu , Charlotte A. Mason, Meghana Killi, Intae Jung, Tiger Yu-Yang Hsiao, Abdurro’uf, Dan Coe, Pablo Arrabal Haro, Steven L. Finkelstein, and Sune Toft.