The lack of Dark Matter in a galaxy may be an oddity, however it has helped astronomers understand how it affects the behavior of the galaxy and its bodies
Dark matter is the form of matter which forms a bulk of the universe. It is unobservable in nature, however it can be detected with its interactions with stars, planets, and other cosmic bodies. Dark matter was first detected in the 1930s when a Swiss astrophysicist observed a group of galaxies, travelling through the universe, much faster than its mass should allow it to. He attributed the excess mass to what we have come to know as dark matter. However, owing to its mysterious nature, dark matter is often a subject of controversy, with some even calling for a complete revamp of physics, as we know it.
In a new discovery, astronomers have been able to prove the existence of dark matter, in a galaxy where there is a dearth of it. Dark matter is a strong gravitational presence. Popular theories state that the substance is actually essential in holding galaxies together. Earlier in 2018, the same group of astronomers stumbled upon a galaxy with almost no dark matter. In this galaxy, the team noted that the system was moving at a speed 6.5 million kmph, which is what its projectile speed should be, accounting for just the weight of the galaxy. The newly found galaxy, also exhibits similar traits, by moving at speeds corresponding to what its mass allows. If the galaxies had a significant amount of dark matter, they would be moving much faster, on par with most star systems.
“Discovering a second galaxy with very little to no dark matter is just as exciting as the initial discovery of DF2 (the newly discovered galaxy), this means the chances of finding more of these galaxies are now higher than we previously thought. Since we have no good ideas for how these galaxies are formed, I hope these discoveries will encourage more scientists to work on this puzzle.” says Pieter van Dokkum, an author on both studies