Around 80 galaxies have been discovered that existed in the early universe. Researchers believe these eventually merged, forming the bigger galaxies that are seen by astronomers today.
In the present universe there are many giant galaxies containing 200 billion stars in disks 100,000 light years across. After the Big Bang, however, nothing like these existed. Instead, it appears pre-galactic clumps formed – cold gas clouds about 100 times smaller than the galaxies seen today. The very first galaxies formed when stars were born within these clumps. They then merged with other clumps to grow in large galaxies.
Research published in The Astrophysical Journal describes some of these galactic clumps, which existed 1.2 billion years after the Big Bang. Scientists used the Subaru Telescope from Japan to initially locate these galaxies. They then used Nasa's Hubble Space Telescope to analyse them individually.
They observed 80 young galaxies, with an average size of under six thousand light years and managed to create images of 54 of these galaxies. Of these, eight appeared to be undergoing the process of merging.
The remaining 46 appeared to be elongated – almost cylindrical. Scientists suggested these were not single galaxies either, and could also be preparing to merge.
The scientists say that in order to identify whether the remaining 46 galaxies are merging or single clusters, they would need to use high angular resolution images; the next stage for their research.
While scientists have been able to observe similar young galaxies before, they have gained little information about their structure because they are so small. These results strongly suggest that galaxies in the early universe did eventually merge to form bigger galaxies that are capable of forming stars.