The largest ever three dimensional map of galaxies and black holes was released by astronomers today. It will help explain the mysterious dark matter and dark energy that they know makes up 96 percent of the universe.
The map is the creation of the Sloan Digital Sky Survey III (SDSS-III) an international project mapping the Milky Way in which a team from the University of Portsmouth is the only UK institution. Early last year, the SDSS-III released the largest-ever image of the sky and astronomers have used new data to expand this image into a full three-dimensional map.
Data Release 9 (DR9) includes images of 200 million galaxies and spectra of 1.35 million galaxies, including 540,000 spectra of new galaxies from when the universe was half its present age. Spectra show how much light a galaxy gives off at different wavelengths. Because this light is shifted to longer redder wavelengths as the Universe expands, spectra allow scientists to work out how much the Universe has expanded since the light left each galaxy.
It will allow better estimates of how much of the universe is made up of dark matter – matter that can’t be seen directly see because it doesn’t emit or absorb light – and dark energy, the even more mysterious force that drives the accelerating expansion of the universe.