The universe began with a spurt of growth

Today, galaxies are growing very slowly. New research shows that things were different in the past.

Galaxies can go through growth spurts just like humans do. In such a stellar galaxy, more stars are formed than usual. Of course, this requires a lot of building materials. Therefore, stellar explosions can form only if they suddenly receive additional gas, for example, from a second nearby galaxy. In this way, the galaxy can experience a growth spurt many times over. You don’t see starburst galaxies very often these days, but researchers at the University of Groningen have shown that they were much more common in the past. They write it in the magazine Astrophysical Journal.

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ultraviolet

This finding required a lot of research using three different telescopes: the Hubble Space Telescope, the Very Large Telescope in Chile and the Spitzer Space Telescope. This allows astronomers to look back in time, as it were. Some galaxies are so far away that their light takes billions of years to reach us. If you know how far galaxies are, you immediately know how old their light is. The galaxies examined in this study are so far away that astronomers are looking back 11 to 13 billion years in time. You can hardly go further, because the age of the universe is 13.7 billion years.

The research team studied more than 20,000 distant galaxies in this way. They are particularly interested in the amount of ultraviolet radiation emitted by galaxies. This indicates the number of stars formed.

Researchers note that in some galaxies a lot of stars are formed in a short time. These were star galaxies. They found that 11 billion years ago, stellar explosions were more common: 20 to 40 percent of all galaxies the team looked at experienced growth spurts. Together, these galaxies made up 60 to 90 percent of the total star production in the early universe.

James Webb

Previously, it was always believed that starbursts were not that important. For the time being only 1 percent All galaxies are a growth spurt. It is not yet known why this was different billions of years ago. It is also interesting that smaller systems in particular have been growing in the past. These galaxies are still very young, and as such they are experiencing a growth spurt for the first time. So it seems that starburst galaxies were very important not only to the formation of stars, but also to the formation of galaxies.

It is remarkable that no one saw this result coming. Astronomers today have very sophisticated models that can predict exactly how galaxies form. But these models say nothing about the starburst. The team believes this is because the processes that cause growth amplifiers occur on a very small scale. As a result, it was overlooked. Therefore the forms are not completed and must be modified. Telescope James Webb Space can help with this. It will soon focus its mirrors on distant galaxies.

sources: ArXiv† Nova

Photo: NASA / European Space Agency