Stockholm university

The light of the first stars electrified the Universe

By the emission of ultraviolet radiation, the first stars transformed the gas in the universe in a process called the reionization of the universe. But how did this happen? Using observations from the James Webb Space Telescope, researchers can now study the early universe with high precision to understand how the first stars and galaxies formed and how they, in turn, affected the surrounding universe as a whole.

Universum
A snapshot taken with the Hubble Telescope of nearly 10 000 galaxies of different ages, sizes, shapes and colours.The red galaxies may be the oldest and most distant galaxies that existed when the universe was only 800 million years old. In the centre is a box showing two galaxies where a bright point is the image of a black hole, information that through in-depth research comes out of the images taken with different types of telescopes. Image: NASA/ESA/Joseph DePasquale (STScI)

Supercomputer calculations open up new knowledge

Using unique observations from the James Webb Space Telescope, the research project will study galaxies at the time of the first stars and galaxies to determine their properties and impact on reionisation. The observations will then be used to develop entirely new supercomputer calculations to describe the physical processes inside galaxies that produced the ultraviolet radiation that drove reionisation, and how it spread throughout the Universe.

Research field: Astrophysics
Project: "Rewriting Cosmic Reionization with Next-Generation Observations of the Early Universe"
Researchers: Matthew Hayes, Angela Adamo, Garrelt Mellema, Göran Östlin, Stockholm University
Grant: SEK 25,000,000 over five years


The universe is in a state of constant evolution. Observations of the early universe, in the first years after the Big Bang, show small fluctuations in the distribution of matter, which gradually grew due to gravity and eventually led to our present universe filled with clusters of galaxies, galaxies, stars and planets.

Studies the first stars and galaxies

One of the most important phases of this evolution was the formation of the first stars and galaxies. With the help of the latest and most powerful telescopes, such as James Webb, it is now possible to study the first stars and galaxies. Their light has traveled for more than 13 billion years to reach our solar system.

”The first generations of stars caused an important change in the universe. Before they came into existence, all the gas in the universe was cold and neutral. Ultraviolet radiation from stars and other objects in the first galaxies heated the gas and ionized it, causing electrons to be released from atomic nuclei,” says Matthew Hayes, associate professor of astrophysics at the Department of astronomy at Stockholm University.

What is known as the "reionization of the universe" started around individual galaxies, but eventually spread throughout the surrounding universe.

”We know it happened, but we still don't understand how it happened,” says Matthew Hayes.

Observations and Computations

The research project "Rewriting Cosmic Reionization with Next-Generation Early Universe Observations" will use unique observations from the James Webb Space Telescope to study galaxies at the time of the first stars and galaxies, to determine their properties and effects on reionization. The observations will be used to develop entirely new supercomputer calculations to describe the physical processes inside galaxies that produced the ultraviolet radiation that drove reionization, and how it spread throughout the universe.

”Our goal is to answer the fundamental questions about the reionization of the universe: When did it start? How did the ionized regions spread through time and space? When did galaxies start ionizing their surroundings? How important are star clusters? And what is the role of black holes? Understanding this is fundamental to understanding how the universe we live in came to be and where we came from,” says Matthew Hayes.

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Last updated: October 17, 2024

Source: Communications Office

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