Dark matter may not be totally ‘dark’ after all. Using the European Southern Observatory‘s Very Large Telescope (VLT) and the Hubble space telescope, astronomers have found signs that the dark matter interacts with something other than gravity. Findings of the study contradict the current theories that suggest that it interacts only with gravity.
Dark matter lags behind in colliding galaxies
Though we know little about the dark matter, it makes up more than 85% of the mass of the universe. It gives galaxies a gravitation pull to retain their structure, stars and planets. Dark matter is invisible, but its impact can be observed using highly sensitive telescopes because it bends light around galaxies, forming a ring of starlight called gravitation lensing.
Scientists led by Dr Richard Massey of Durham University used the VLT and Hubble to zoom in on four colliding galaxies in the Abell 3827 galaxy cluster, which is 1.3 billion light years away from Earth. While mapping out the distribution of dark matter in these four colliding galaxies, researchers found that the dark matter associated with each galaxy was out of alignment with its galaxy.
The dark matter clump was lagging about 5,000 light-years behind the normal matter in each of these galaxies. That is the distance NASA’s Voyager spacecraft would take 90 million years to travel, according to The Telegraph. It indicates that something other than gravity is preventing the dark matter from staying in its rightful place. Such an offset is possible only if it interacts with forces other than gravity.
Dark matter interacts with the world around it
Dr Richard Massey said it could be the first evidence that dark matter notices and interacts with the world around it. It may not be completely dark after all. Findings of the study were published on April 15 in the journal Monthly Notices of the Royal Astronomical Society. Researchers believe that the dark matter halos have a net drag effect on one another when galaxies collide.
Massey said that scientists are finally “homing in from dark matter from above and below.”