Here's a bit more info about the newly discovered primordial population of compact and ultra-blue galaxies. More info can be read at The Hubble Site.
Three teams worked hard to find these new galaxies and did so in a burst of papers immediately after the data were released in September, soon followed by a fourth team, and later a fifth team. The existence of these newly found galaxies pushes back the time when galaxies began to form to before 500-600 million years after the Big Bang. This is good news for astronomers building the much more powerful James Webb Space Telescope (planned for launch in 2014), which will allow astronomers to study the detailed nature of primordial galaxies and discover many more even farther away. There should be a lot for Webb to hunt for.
The deep observations also demonstrate the progressive buildup of galaxies and provide further support for the hierarchical model of galaxy assembly where small objects accrete mass, or merge, to form bigger objects over a smooth and steady but dramatic process of collision and agglomeration. It's like streams merging into tributaries and then into a bay.
These galaxies are as small as 1/20th the Milky Way's diameter," reports Pascal Oesch of the Swiss Federal Institute of Technology in Zurich. "Yet they are the very building blocks from which the great galaxies of today, like our own Milky Way, ultimately formed," explains Marcella Carollo, also of the Swiss Federal Institute of Technology in Zurich. Oesch and Carollo are members of Illingworth's team.
These newly found objects are crucial to understanding the evolutionary link between the birth of the first stars, the formation of the first galaxies, and the sequence of evolutionary events that resulted in the assembly of our Milky Way and the other "mature" elliptical and majestic spiral galaxies in today's universe.