Scientists in Japan and the U.S. have discovered about 80 young galaxies that existed just 1.2 billion years after the Big Bang with some help from the Subaru Telescope, which allowed them to learn a bit more about compact galaxies that existed in the early universe.
We are living about 13.8 billion years after the Big Bang. At this point in time, there are a lot of giant galaxies, such as our own Milky Way galaxy. Just after the Big Bang, though, galaxies had only just started to form, which means that many of them were far smaller.
A team of researchers from Ehime University, Nagoya University, Tohoku University, the Space Telescope Science Institute and the California Institute of Technology believes that pre-galactic "clumps" formed in the universe about 200 million years after the Big Bang. These clumps were, in reality, cold gas clouds with relatively small masses in comparison to today's giant galaxies. The clumps were eventually drawn together and eventually grew big enough to form larger galaxies.
However, these events have remained elusive to scientists, and because most galaxies in the young universe were small, seeing their detailed structure has been difficult.
In this latest study, however, the researchers used the Subaru Telescope and the Hubble Space Telescope to find early galaxies in addition to examining their internal structures. First, they used the Subaru Telescope to actually find the early galaxies and then used the Hubble Space Telescope in order to study them in more detail.
So what did the researchers find? It turned out that eight of the 54 galaxies that they found actually had a double-component structure, in which two galaxies seemed to be merging with each other. However, they were unsure as to whether the remaining 46 galaxies were single galaxies. In order to find out, they conducted computer simulations. In the end, the simulations showed that it was likely that most were actually two merging galaxies that were so close that they couldn't be seen as single.
So what does this mean? It's likely that the most active galaxies also have the smallest sizes. As these galaxies merge, they trigger intense star formation that helps create even larger galaxies.
The findings reveal a bit more about galaxies in the early universe. More specifically, they show how smaller galaxies merged together to eventually create the larger galaxies that we see today.
The study was published in the Feb. 24 issue of the The Astrophysical Journal.
