NASA has released an image of a newly discovered galaxy that is the youngest object seen so far. The young dwarf galaxy, named MACS0647-JD, is only 600 light-years across and is seen only 420 million years after the Big Bang (13.3 Billion light-years away from Earth).
The galaxy is tiny. For comparison, the Large Magellanic Cloud, a dwarf galaxy companion to the Milky Way, is 14,000 light-years wide. Our Milky Way is 150,000 light-years across.
The image above is a composite taken with Hubble’s Wide Field Camera 3 (WFC 3) and the Advanced Camera for Surveys ( ACS) on 5 October and 29 November 2011. The work was done by the Cluster Lensing And Supernova Survey with Hubble (CLASH) team.
Dark Energy drives the accelerating expansion of the Universe, and the imprint can be found in the distribution of galaxies.
Now, researchers, including several associated with the University of Arizona in Tucson, have published a series of six papers (see below) concerning the distribution of galaxies 5.5 billion light years from Earth, using data from the Sloan Digital Sky Survey.
The papers detail how mapping the position of galaxies can measure how fast the Universe was expanding six billion years ago. The expansion is the result of Dark Energy, which makes up 72% of the universe in which we live (the remainder is Dark Matter (23%) and atoms (5%), found in intergalactic gas and stars).
The image above illustrates how variations in the cosmic microwave background (due to baryon acoustic vibrations during inflation, which followed the Big Bang) are reflected by later distribution of galaxies, and measuring the distribution of galaxies at different times reflects the accelerating expansion of the universe. The original work on the accelerating expansion came from observations of type Ia supernovae in 1998 and and 1999, and led to the Nobel Prize in 2011.
The Baryon Oscillation Spectroscopic Survey (BOSS) is one of four SDSS surveys, and the team of scientists and engineers that make up the team are the authors of these six papers.
Will Percival, a professor at the University of Portsmouth in the United Kingdom, and one of the leaders of the analysis team noted that:
This coupled with the previously released data on the distribution of galaxies at 3.8 billion light years, shows the accelerating expansion: the rate at 3.8 billion light years is more than the earlier rate at 5.5 billion light years.
Due to the original oscillations in the universe, theory predicts that the average distance between galaxies would be 500 million light years. And this is what the BOSS results have shown. They are the best measurements to date.
From the SDSS article we have the references to the arxiv papers: