Astrophysicists are in for a big surprise as they realize more and more that dark matter could be even more mysterious than previously believed.
Dark matter is still more on the unknown side of science, a variety of “stuff” amounting to almost 85 percent of the Universe’s mass; standard matter, the one scientists understand better, occupies a less part of the Universe as we know it.
An international team of scientists studied huge clusters of galaxies and the way they collide, and their main surprise was that dark matter doesn’t appear to interact with anything during such turmoil.
No one theory regarding dark matter has managed to gain enough traction in the field so far. This study about the collisions of galaxies has been published in the journal Science. There is one theory, however, that many astronomers choose to believe: they say an unknown and yet undiscovered subatomic particle is responsible for dark matter.
Others diss this theory and tend to support the idea that dark matter is the result of a quantum defect that dates back to the birth of the Universe, an altered gravity. The most eccentric call it “a type of extra-dimensional mass”.
One of the evidences that point to the existence of dark matter is the way cosmic structures behave when they interact with it – they are reshaped and molded by it. Light is also bent when passing through dark matter, which distorts the way we perceive distant space objects.
The other known fact is that galaxies movement inside galaxy clusters is accelerated by dark matter. A galaxy cluster is a collection of hundreds of galaxies made up from unimaginable amounts of planets, stars and gases.
And given the fact that dark matter is the main element of most galaxy clusters, these space collections represent the perfect environment for studying the behavior of dark matter. The most ideal situation for studying them is created when galaxies crash into each other, forcing their respective amounts of dark matter to interact.
David Harvey from EPFL’s Laboratory of Astrophysics is fascinated by galaxy cluster collisions and he studies them in order to gain insight about the elusive nature of dark matter. His study, created in partnership with his colleagues contains data gathered and then analyzed from 72 galaxy cluster collisions.
Their purpose was to determine is the momentum of dark matter was altered during and after the two galaxy cluster collided. Studying the galaxies’ behavior helps scientists draw conclusions about the nature of dark matter.
Further investigation is required before they can be sure about the scenarios that take place in the vastness of space: scientists believe that either the dark matter particles collide frequently but exchange little momentum, or they seldom interact and exchange huge amounts of momentum.
Image Source: NASA