A comparative study of MOND and MOG theories versus the κ-model: an application to galaxy clusters

Abstract

Many models have been proposed to minimize the dark matter (DM) content in various astronomical objects at every scale in the Universe. The most widely known model is MOdified Newtonian dynamics (MOND). MOND was first published by Mordehai Milgrom in 1983. A second concurrent model is modified gravity, which is a covariant scalar–tensor–vector extension of general relativity. Other theories also exist but have not been broadly applied to a large list of astronomical objects. Eventually, we can also mention the Newtonian fractional-dimension gravity, a gravity theory based on spaces with fractional (i.e., non-integer) dimension. A new model, called κ-model, based on very elementary phenomenological considerations, has recently been proposed in the astrophysics field. This model shows that the presence of DM can be considerably minimized with regard to the dynamics of galaxies. The κ-model belongs to the general family of theories descended from MOND. Under this family of theories, there is no need to develop a highly uncertain DM sector of physics to explain the observations.