The scientists propose a new theory that can explain the nature of the mysterious lack of dark matter in two galaxies. The researchers at the University of California believe that dark matter is capable of self-interaction. That hypothesis helps to explain why two galaxies located about 65 million light years from the Earth contain so little of the mysterious dark matter. As you know, dark matter may be invisible, but at the same time it makes up about 85% of all matter in the Universe, although its nature is unknown.
Unlike ordinary matter contained in space, dark matter does not absorb the light, does not emit it, does not reflect and it makes it difficult to search and detect. It is known as cold dark matter.
The scientists assume that dark matter particles do not collide, the only exception is gravitational force. But if we take into account the new theory of self-interacting dark matter, then its particles can self-interact with each other. Thus, one can explain the emergence of the general structure of the Universe on the basis of the assumption of the distribution of dark matter inside the galaxy.
The new theory does not exclude that in the case the particles collide with each other in the region of the inner halo of the galaxy that may locate near the center. A physicist Hai-Bo Yu believes that any visible galaxy is surrounded by a halo of dark matter. It is a kind of concentrated ball-shaped lump that surrounds the galaxy and is held in one place by gravitational forces.
Recent observations of two galaxies, NGC 1052-DF2 and NGC 1052-DF4, have shown that they either have no dark matter at all, or very little of it. That conclusion complicates the understanding of the formation of galaxies. It is possible that both galaxies are companion galaxies of NGC1052.
And although it is generally accepted that dark matter prevails over the mass of the galaxy, in the case the opposite is observed, the ratio can be 300 times less. And most of the dark matter of the galaxy can be lost due to tidal phenomena with the massive galaxy NGC1052.
Satellite galaxies are not able to contain the excess mass by their gravitational forces, and therefore it can add to the mass of NGC1052. The scientists intend to conduct a more detailed study of the galaxy in order to find any evidence of their theory or disprove it.