But a team at the University of California at Riverside (UCR) has given an explanation for the puzzle – it’s being stripped away from a larger nearby galaxy. The idea that the universe contains a lot of invisible matter dates back to the 1930s. Astronomers at the time found that distant galaxies move much faster than their visible mass. That means there’s a lot more behind the scenes mass behind it than they can see, so-called “dark matter.”. < p > < p > in the decades after that, astronomy continued to prove the existence of dark matter through observations. Although it is still difficult to find the dark matter itself, some of the most powerful evidences supporting the idea lie in the mystery of existence and non existence. < / P > < p > in 2018, astronomers announced a surprising discovery: a dwarf NGC 1052-df2 (df2) galaxy with almost no dark matter. The high proportion of visible matter may be explained by its relatively slow motion speed. Then the next year, astronomers discovered another similar light galaxy, NGC 1052-df4 (DF4 for short). These “exceptions” provide a strong support for the dark matter theory, after all, opponents have suspected that the dark matter theory originated from the wrong model calculation. If so, opponents will find it hard to explain why this theory applies to almost all galaxies. < / P > < p > now, a new study from the University of California at Riverside (UCR) looks into where dark matter in these galaxies might disappear. Both df2 and DF4 are satellite galaxies that orbit the larger NGC 1052. Astronomers believe that tidal forces in large galaxies are pulling mass away from light galaxies. “It is generally believed that dark matter dominates the overall mass of the galaxy,” said Yu Haibo, chief researcher of the galaxy. However, observations of df2 and DF4 show that the ratio of dark matter to stellar mass is close to 1, only 1 / 300 as expected. To explain this huge difference, we think that df2 and DF4 may be under the tidal force of NGC 1052, stripping most of its mass. “. < p > < p > simulating the interaction between three galaxies by two suggested dark matter types seems to provide a reliable explanation for the mechanism of this process. However, some interesting viewpoints are still introduced in some advanced researches in the industry. For example, some models show that dark matter is in a “cold state”, and the examples move slowly and have little interaction with each other. However, recent theories suggest that there may be a new “dark energy” that strongly binds them together. Both of them explain the large-scale structure of the universe, but have different meanings for the dark matter in the center of the galaxy. < / P > < p > by modeling dwarf galaxies with two types of dark matter, the researchers found that tidal stripping could work in both cases. It may also be easier to understand for self interacting dark matter. It is speculated that this interaction pushes more dark matter particles from the center of the galaxy to the outer region, making it easier to peel off. < / P > < p > even so, other studies have come to different conclusions, such as the belief that df2 does not lack dark matter at all, and attribute the differences to the miscalculation of Galaxy distances. Details of the study have been published in the recently published Physical Review Letters. Global Tech