Scientists have just been able to look back in time to see the collision of young galaxies as it happens. Astronomers have dated these events to happen about 12 billion years ago or one billion years after the Big Bang.
Originally, scientists thought that what they were witnessing happened three billion years after the Big Bang.
A Mega Galaxy Cluster
Researchers from Dalhousie University, Yale University, and the University of Edinburgh used the Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Pathfinder Experiment (APEX) to view the galaxies as they are colliding. They had to view 90 percent across the observable universe to be able to see how these galaxies are combining. Scientists have named the protocluster SPT2349-56.
This is the most active region that scientists have observed in space. Just in this region thousands of new stars are formed every year, whereas in the Milky Way galaxy just one new star is born every year. The light produced by these galaxies began traveling towards Earth when the Universe was only one billion years old.
Scientists used computer simulations to forecast that with time the galaxies will form a massive galaxy cluster. This would make the structure one of the largest things in the universe. Researchers published their findings in the journal Nature.
Co-author of the study Chris Hayward says that this finding is the closest that scientists have been able to get to see a galaxy cluster form. He calls it the missing link in understanding how galaxy clusters are formed.
Tracing The Galaxy Clusters
Scientists still don't know how galaxy clusters are formed in the universe. Galaxy clusters are the largest structures that are caused by gravity in the universe, and can be made up of thousands of galaxies. Clusters grow as the gravity draws more objects into the cluster.
Researchers stumbled upon the galaxy cluster while doing follow-up research for a project to examine almost six percent of the sky. Those observations were made with the South Pole Telescope in Antarctica but they were fuzzy. It wasn't until they used ALMA that they were able to get a look at what they were actually witnessing.
SPT2349-56 contains the mass of around 10 trillion suns. Computer simulations show that the 14 galaxies will combine into one massive galaxy cluster rather than move away from each other. They would combine over the next one billion years, growing into an elliptical galaxy.
Researchers say that the amount of star formation in one region could be an indicator of a cluster forming. Hayward says that the gravitational pull from the other galaxies may be compressing gas in galaxies, triggering the formation of stars.