Astrophysicists from the Universities of Bonn and St. Andrews studied the behavior of dwarf galaxies in the cluster
Dwarf galaxies are small, faintgalaxies that are commonly found in galaxy clusters or near larger galaxies. Because of this, they can be affected by the gravitational influence of their larger satellites. The Furnace Cluster, one of the closest to Earth, is located at a distance of about 62 million light-years. It is richly populated by dwarf galaxies.
Recent observations show that some ofthese "dwarfs" appear distorted, as if they were perturbed by the environment of the cluster. Based on the standard cosmological model, astrophysicists calculated the expected level of disturbance of galaxies, which depends on their internal properties and the distance to the powerful gravitational center of the cluster. The scientists compared the data obtained with the changes that are visible in survey photographs taken by the VLT telescope of the European Southern Observatory.
Galaxy NGC1427A is one of the “dwarfs” of the Fornax cluster. Image: ESO
The results of observations did not correspond to the calculations.If we use the standard cosmological model, then the gravitational influence from the center of the cluster should have long ago torn apart dwarf galaxies. For comparison, scientists tried to model the behavior of galaxies in terms of an alternative MOND theory. To their surprise, it turned out that this theory completely explains the observed distortions of the "dwarfs".
We were not sure that dwarf galaxieswould be able to survive the extreme conditions of MOND galaxy clusters due to the lack of protective dark matter halos in this model, but our results show a remarkable agreement between observations and MOND expectations regarding the level of distortion of the "dwarfs" of the Furnace.
Indranil Banik, co-author of the study at the University of St. Andrews
According to the standard cosmological model,the vast majority of galaxies are surrounded by a halo of dark matter particles. This halo is invisible, but its mass exerts a strong gravitational pull on neighboring galaxies. In particular, it should protect galaxies from the action of external gravitational forces.
Instead of assuming dark matter halos,surrounding galaxies, the MOND theory offers a correction to the Newtonian dynamics, due to which gravity is strengthened in the regime of small accelerations. Previously, Hi-Tech spoke in detail about an alternative cosmological theory.
Cover image: The Furnace Cluster. Photo: ESO, Aniello Grado, Luca Limatola
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