Dark matter is the kind of matter which is cannot be seen by the telescope but accounts for most of the matter in the universe. It constitutes around 84.5 percent of the total matter in the universe. It is invisible because it does not emit light. Its effects can be seen by studying its effects through gravitational lensing.
Gravitational lensing is the phenomenon when the gravitational pull of dark matter bends light around distant galaxies.
The dark Energy Survey is a collaboration of more than 300 scientists from 25 institutions in six countries. The primary instrument is dark energy camera, a 570 megapixel imaging device.
The main aim of the survey is to understand the role of the dark matter which will in turn help in understanding the role of dark energy, which is responsible for the expansion of the universe.
Scientists for the first time have released maps on dark matter. These maps are the largest contiguous maps created at this level of detail, and will help in understanding the dark matters role in galaxy formations. Analysis on the clumpiness of the dark matter in the maps will help scientists to prove the nature of dark energy.
At the American Physical Society in Baltimore, Maryland, the new maps were released.
The analysis was led by Vinu Vikram of Argonne National Laboratory then at the University of Pennsylvania and Chihway Chang of ETH Zurich.
Vikram said, “We measured the barely perceptible distortions in the shapes of about 2 million galaxies to construct these new maps, they are a testament not only to the sensitivity of the Dark Energy Camera, but also to the rigorous work by our lensing team to understand its sensitivity so well that we can get exacting results from it.”
The map released used early DES observation and covers only about three percent of the area of the sky DES will document over its five year mission. The survey has covered its second year.
This research will help scientists to test current theories.
The theories suggest that, since there is more dark matter than visible matter, galaxies will form where there is large concentration of dark matter since there is strong gravity. The DES analysis backs this theory where in cosmic voids few galaxies are found and large number of galaxies is found where there is huge concentration of dark matter.
Chang said, “Our analysis so far is in line with what the current picture of the universe predicts, zooming into the maps, we have measured how dark matter envelops galaxies of different types and how together they evolve over cosmic time. We are eager to use the new data coming in to make much stricter tests of theoretical models.”