A cluster of dwarf galaxies at Earth's second closest distance from dark matter is devoid of dark matter haloes

Dark matter is always mentioned by astronomers as an enigmatic, unseen substance that fills the cosmos. The majority of galaxies are surrounded by halos that contain them.

The mass of the halo exerts a strong gravitational influence on the galaxy itself and other galaxies nearby. According to that theory, dark matter positively affects galaxies. However, the concept of such halos is not without flaws. There are some dwarf galaxies with strange shapes that lack halos.

According to the 'standard model' of cosmology, galaxies are protected from their nearby neighbors by dark matter halos. According to a study conducted by the universities of Bonn and Saint Andrews, this view is being challenged.

The Fornax Cluster, the second closest galaxy cluster to Earth, does not have dark matter halos. Royal Astronomical Society's Monthly Notices published the findings.

The principal author of the study Elena Asencio said, 'We introduce an innovative way to test the standard model by measuring how much dwarf galaxies are disturbed by gravitational tides from larger galaxies nearby.'

In general, dwarf galaxies are located in or near larger galaxies or galaxy clusters. Hence, they may be affected by their larger neighbors' gravitational effects. According to recent research, some of these dwarfs appear to have distorted appearances.

The Standard Model does not predict such perturbations in the Fornax dwarfs, explained Pavel Kroupa, Professor at the University of Bonn and Charles University in Prague, adding that the dark matter halos of these dwarfs should partially shield them from tides brought on by the cluster.

Dwarfs' expected disturbance level was calculated based on internal characteristics and distances from gravitationally strong cluster centers.

Based on the comparison, Asencio stated, 'The Fornax dwarfs should already be destroyed by gravity from the cluster center if one wishes to explain the observations in the standard model, even when the tides raised by the center are 64 times weaker than their gravity.'

In contrast, earlier research has found that the force required to perturb a dwarf galaxy is roughly equal to its gravity. Therefore, the mainstream paradigm cannot account for the observed Fornax dwarf morphologies self-consistently.

Hongsheng Zhao from the University of St Andrews said their findings have important implications for fundamental physics and that they expect to find further perturbed dwarfs in other clusters.