Scientists at the University of California at Riverside have found traces of a new type of fundamental interaction, confirming one of the theories of the nature of dark matter in the Universe. This theory explains why a pair of galaxies 65 million light-years from Earth contain little mysterious matter. This is reported in an article published in the journal Physical Review Letters.
According to the prevailing CDM theory, dark matter is cold, that is, it interacts weakly with ordinary matter and electromagnetic radiation, manifesting itself only through gravity. An alternative view, called the SIDM theory of self-interacting dark matter, suggests that dark matter particles interact with each other through a new, dark force. Both theories predict the observable structure of the universe, but differ in the distribution of dark matter in the inner regions of the galaxy.
SIDM suggests that dark matter particles interact strongly with each other in the inner halo of the galaxy, near its center. This explains why the two low-luminosity ultradiffuse galaxies NGC 1052-DF2 and NGC 1052-DF4 are calculated to contain very little dark matter. Usually visible galaxies have a significant amount of dark matter in the form of a ball, which affects the movement of stars in it and is held by gravity.
Both galaxies are satellites of the galaxy NGC 1052. With the help of simulations, scientists reproduced the loss of matter NGC 1052-DF2 and NGC 1052 due to the tidal forces of NGC 1052. It turned out that under these conditions and within the framework of SIDM, the formation of galaxies with a deficit of dark matter is more likely than in the case of CDM. In the latter variant, the structure of the inner halo is “rigid” and resistant to tidal discontinuities.
