Birth of the earliest galaxies in the universe observed for the first time

Using the James Webb Space Telescope, researchers from 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 knowledge about the universe and has now been published in Science.

For the first time in the history of astronomy, researchers from the Niels Bohr Institute have witnessed the birth of three of the very earliest galaxies in the universe, somewhere between 13.3 and 13.4 billion years ago.

The discovery was made using the James Webb Space Telescope, which brought these first ‘live observations’ of formative galaxies to us here on Earth.

Through the telescope, researchers were able to see signals of large amounts of gas accumulating and ending up in a mini-galaxy under construction. Although this is how galaxies form according to theories and computer simulations, it had never been observed before.

‘You could say these are the first ‘direct’ images of galaxy formation we have ever seen. While the James Webb has previously shown us early galaxies in later stages of evolution, here we are witnessing their birth, and therefore its birth. construction of the first galaxies in the universe,” says Assistant Professor Kasper Elm Heintz of the Niels Bohr Institute, who led the new study.

Galaxies born shortly after the Big Bang

The researchers estimate that the birth of the three galaxies occurred about 400 to 600 million years after the Big Bang, the explosion that started it all. While that seems like a long time, it is equivalent to galaxies forming during the first 3 to 4% of the universe’s total 13.8 billion year lifespan.

Shortly after the Big Bang, the universe was a vast opaque gas of hydrogen atoms – unlike today, where the night sky is speckled with a blanket of clearly defined stars.

‘During the few hundred million years after the Big Bang, the first stars were formed, before stars and gas began to combine into galaxies. This is the process we see the beginnings of 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 Age of Reionization, when the energy and light of some of the first galaxies broke through the nebulae of hydrogen gas.

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

Contributes to the understanding of our origins

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

The research team has already requested more observing time with the James Webb Space Telescope, hoping to extend their new result and learn more about the earliest epoch in galaxy formation.

‘For now, this is about mapping our new observations of galaxy formation in even more detail than before. At the same time, we are constantly trying to push the boundaries of how far we can see into the universe. So maybe we can reach even further,” says Vejlgaard.

According to the researcher, the new knowledge contributes to answering one of humanity’s most fundamental questions.

“One of the most fundamental 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 the moment when some of the universe’s first structures were created. It’s a process we’ll explore further, until we can hopefully fit even more pieces of the puzzle together to put in place,” 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.