While they still don’t know what dark matter is, scientists using data collected by NASA, now know a little more about what it’s not.
After analyzing two years’ worth of data from NASA’s Fermi Gamma-ray Space Telescope, they’ve eliminated four possible types of particles thought to make up the mysterious substance.
Experts theorize about 80 percent of matter in the universe can’t be seen by telescopes.
But they know something is there because of its gravitational influence over the orbital speeds of stars around galaxies and how clusters of galaxies move within the universe.
This so-called “dark matter” forms most of the universe, yet it neither gives off nor absorbs light or any other electromagnetic radiation.
Scientists think the key to its identity will be the discovery of new types of subatomic particles that are quite different from those that make up the atoms of visible and known matter that surrounds us.
Among the new particles scientists have favored to form dark matter are those called “Weakly Interacting Massive Particles” or WIMPS. Scientists think some of these particles are destroyed when pairs of them interact with each other, producing gamma rays – the most energetic form of light – at the same time.
With this in mind, the team set out to see if the gamma ray signals from 10 dwarf galaxies are consistent with the high-energy radiation produced from the destruction of four different types of WIMP particles, thought to be associated with dark matter.
Rather than analyzing each of the galaxies separately, the scientists developed a statistical technique that allowed them to evaluate all of the galaxies at once.
The analysis showed none of the gamma ray signals they studied are consistent with those that could be produced by these four classes of WIMP particles and therefore could not be dark matter.
So, as scientists continue their investigation into dark matter, at least they now have four classes of WIMP particles that have been eliminated from consideration.