WASHINGTON (Reuters) – Dark matter, the mysterious invisible stuff that makes up most of the mass of galaxies including our own Milky Way, is again confusing scientists, with new observations of distant galaxies conflicting with current understanding of its nature. .
Research published this week revealed an unexpected discrepancy between observations of dark matter concentrations in three massive galaxy clusters comprising trillions of stars and theoretical computer simulations of how dark matter should be distributed.
“Either there is a missing ingredient in the simulations or we have made a fundamental wrong hypothesis about the nature of dark matter,”
Dark matter is the invisible glue that holds the stars together within a galaxy. It also creates an invisible scaffold that allows galaxies to form clusters. But it has very peculiar properties. It does not emit, absorb or reflect light and does not interact with known particles.
Most of the matter in the universe, around 96%, is thought to be dark matter, with ordinary matter – the visible matter that makes up stars, planets and people – only 4%.
The presence of dark matter is known only through its gravitational pull on visible matter in space. It differs from the equally enigmatic and invisible dark energy, which is considered a property of space and is driving the accelerated expansion of the universe. Dark energy is repulsive. Dark matter attracts through gravity.
The new study involved observations from the Hubble Space Telescope and the Very Large Telescope of the Southern European Observatory in Chile.
When light from distant sources such as distant galaxies travels through matter such as another galaxy or a cluster of them, the light is deflected and bent – a phenomenon called “gravitational lensing,” said the astrophysicist and lead author of the Massimo Meneghetti studio of the Observatory of Astrophysics and Space Sciences of Bologna and National Institute of Astrophysics in Italy.
The new observations showed that the gravitational lensing effects produced by galaxies residing within huge galaxy clusters were much stronger than current dark matter theory predicted, suggesting an unexpectedly large concentration of dark matter in these galaxies.
“This is quite surprising,” Meneghetti said.
Will Dunham Reporting; Editing by Sandra Maler