Scientists from the University of California used sophisticated computer simulations to create a test to prove or disprove the existence of dark matter. The analysis shows that the answer lies in the movement of stars in small satellite galaxies orbiting the Milky Way.
Using one of the fastest supercomputers in the world, researchers modeled the distribution of matter in satellite dwarf galaxies. These are small galaxies revolving around large ones, such as the Milky Way or Andromeda.
The researchers focused on radial acceleration (RAR). In disk galaxies, stars move in circular orbits around the galactic center. The acceleration that causes them to change direction is caused by the attraction of matter. RAR describes the relationship between this acceleration and what is caused only by visible matter. It gives an idea of the galactic structure and distribution of matter.
Distribution of dark matter (above) and stars (below)
For the first time, RAR simulation of dwarf galaxies was performed taking into account the presence of dark matter. It turned out that they behave like smaller versions of larger galaxies. But what if there is no dark matter, and gravity contradicts Newton's laws? Then the RAR of dwarf galaxies strongly depends on their distance to the host galaxy, which does not happen if there is dark matter. This difference turns satellite galaxies into powerful tests to check for dark matter. In 2013, the ESA Gaia spacecraft was launched, which can answer this question. It was created for the unprecedented study of stars in the Milky Way and satellite galaxies. There is a lot of data, so the analysis will take years.
Glue for galaxies
This question is still the most relevant in cosmology. The existence of dark matter suggested more than 80 years ago. This was done by Fritz Zwicky, who guessed that galaxies were moving so fast in clusters that they were actually moving away from each other. Therefore, he suggested the presence of invisible matter, which is endowed with sufficient gravity to save galaxies in their orbits. In the 1970s Vera Rubin noticed a similar phenomenon in spiral galaxies.
Today, most of the scientific world is convinced that dark matter occupies about 80% of the universal mass. It is not in contact with the light, so it is invisible to telescopes. But its theoretical existence fits perfectly into other observations, like the distribution of the CMB radiation. In addition, it explains the location and speed of the formation of galaxies. But so far it has not been possible to prove its existence, so some people think that gravity does not conform to generally accepted laws. Future discoveries will show who was right.