Dark matter is one of the greatest mysteries of our universe. We know it is out there in the vast void of space but we can never observe it – directly at least.
It doesn’t emit any light or interact with the matter that we know off. Scientists suspects dark matter to be made of some new types of constituents, quite different from our electrons and protons.
This invisible material is said to be a gravitational glue that holds our galaxies together. 27% of all mass in the universe is supposed to be made up of dark matter. Although we can’t “see it” we can detect its presence by measuring the effect it has on other celestial bodies.
Over the years scientists have come up with various theories trying to explain the nature of dark matter.
One widely accepted theory on dark matter is the theory of cold dark matter. The central idea behind the theory is that dark matter doesn’t move fast making it easier to forms clumps of varying sizes – small to large. This idea suggests that the universe is filled with a broad range of dark matter concentrations.
Now scientists from NASA might just have found the evidence in support for this theory. Their analysis of Hubble data using a new observation technique has allowed them to detect small clumps of dark matter. NASA reveals the newfound dark matter to be 100,000 times less massive than the dark matter “Halo” they found previously on Milky Way.
The researchers found the little clumps of dark matter by looking at the “gravitational lensing” of faraway quasars by massive galaxies that exist before them in our line of sight. Gravitational lensing is an effect that was predicted by Einstein’s general theory of relativity.
Under gravitational lensing, the light away from far ever stars get warped around due to the gravity of galaxy that’s before them in a such a way that at certain positions of observation the stars appear as four distorted light source. The resulting observation is called Einstein’s cross and the causing galaxy becomes a “gravitational lens”.
In the new research, scientists studied how the light from the quasar gets warped by the galaxy and the position of apparent images (distorted images of the star). Then they created a scenario of how the Einstein cross will look without accounting the mass of dark matter.
Comparing both – the observed lensing and predicted lensing they were able to identify the mass of dark matter. The use of this approach led them to the new discovery. Anna Nierenberg, a researcher at NASA’s Jet Propulsion Laboratory who led the Hubble survey, said that “Astronomers have carried out other observational tests of dark matter theories before, but ours provides the strongest evidence yet for the presence of small clumps of cold dark matter. By combining the latest theoretical predictions, statistical tools and new Hubble observations, we now have a much more robust result than was previously possible.”
The researchers will be presenting their observation results at the 235th meeting of the American Astronomical Society in Honolulu, Hawaii. As scientists continue their studies on the dark matter they are indeed becoming less mysterious.