Everyone is familiar with ordinary matter, which makes up the “stuff” of the universe. Dark matter is much more mysterious, but is believed to make up about 85% of all matter in existence. A new paper published in Nature by an international collaboration of researchers claims to have found evidence of this elusive dark matter right in the inner Milky Way.
“In our new study, we obtained for the first time a direct observational proof of the presence of dark matter in the innermost part of the Milky Way,” co-author Miguel Pato from Stockholm University explained in a press release. “We have created the most complete compilation so far of published measurements of the motion of gas and stars in the Milky Way, and compared the measured rotation speed with that expected under the assumption that only luminous matter exists in the Galaxy. The observed rotation cannot be explained unless large amounts of dark matter exist around us, and between us and the Galactic centre.”
Prior research has found evidence of dark matter in the outer reaches of the galaxy, but this is the first to report it from the inner region. Because dark matter does not interact with light or radiation at all, it cannot be seen, and therefore must be observed indirectly. This can primarily be done by watching the effects of gravity acting on ordinary matter, such as the rotation of gas and stars within a galaxy. Detecting dark matter is easier to do on the outer fringes of the Milky Way, but it becomes difficult to see these effects on the inner galaxy because of our proximal vantage point and high mass density.
The current paper is the first to provide evidence of dark matter’s influence on the inner galaxy. This was accomplished with the use baryonic mass distribution models, which were compared to the rotational curves of the galaxy. Moving forward, the scientists will continue their quest for more evidence of dark matter in order to better understand this ambiguous material.
“Our method will allow for upcoming astronomical observations to measure the distribution of dark matter in our Galaxy with unprecedented precision,” Pato explained. “This will permit to refine our understanding of the structure and evolution of our Galaxy, and it will trigger more robust predictions for the many experiments worldwide that search for dark matter particles. The study therefore constitutes a fundamental step forward in the quest for the nature of dark matter.”