Astronomers discover how galaxies form through mergers
Examples of galaxy pairs found in this study—here are examples of detected systems which are within close proximity to each other. Credit: C.Conselice et al

Our own Milky Way formed over 10 billion years ago through an abundance of separate galaxies colliding.

The origin of Galaxies, the largest object in the universe, is a very old question with no obvious answers. This problem has been solved by a major study submitted to The Astrophysical Journal.

The effect of merging is one of the main processes that lead to the creation of the universe.

The study concluded that galaxy mergers are one of the most important ways to form a galaxies. Over the past 10 billion years, the average massive galaxy will undergo 3 mergers, which will more than double their mass. The study shows that mergers are a very effective way to form a new group of objects.

It's possible that our own Milky Way galaxy has undergone at least one of these mergers, which changed its shape and formation history. Mergers may be the origin event for how stars including our own Sun formed as well as feeding the matter that grows central black holes.

There are all sorts of Galaxies in the universe. Some of them are very large with a lot of stars and spirals. There are huge collections of stars with no specific patterns. The history of these systems isn't well known.

The process of merging is one way in which galaxies can grow in mass. Over half a century has passed since the first galaxy mergers, but their role in how we obtain the massive galaxies we see today is still a mystery. We were only able to guess at how the process had actually happened.

The result of the study was searching back 10 billion years for galaxies that were in pairs. A new system will be formed over the course of a billion years. This study was able to determine the merger history and the formation history of the universe. Only theoretical estimates of this have been available before. The study is about the process.

Over the past 10 billion years, there have been about 2 trillion merger events in the universe. The most common massive coalescence events to occur in the universe will be visible with the upcoming experiments.

This previously unknown history gives us a better understanding of the universe. Future work by this team and others will show the implications for understanding the development of new stars and black holes in the universe.

More information: Leonardo Ferreira et al, A Simulation-driven Deep Learning Approach for Separating Mergers and Star-forming Galaxies: The Formation Histories of Clumpy Galaxies in All of the CANDELS Fields, The Astrophysical Journal (2022). DOI: 10.3847/1538-4357/ac66ea Journal information: Astrophysical Journal