The vast majority of galaxies are surrounded by a halo of dark matter particles, according to the accepted theory of cosmology. Although invisible, the mass of this halo pulls nearby galaxies into a strong gravitational field.
This understanding of the universe is being challenged by recent research from the Universities of Bonn and Saint Andrews in Scotland. The results indicate that the dwarf galaxies in the Fornax cluster, the second closest cluster of galaxies to Earth, are free of such dark matter halos. The study appeared in Monthly Bulletins of the Royal Astronomical Society.
Dwarf galaxies are small, inconspicuous galaxies that are commonly seen in galaxy clusters or near larger galaxies. They could therefore be influenced by the attraction of their larger conspecifics.
We present an innovative method for testing the Standard Model based on how much dwarf galaxies are perturbed by gravitational tides from nearby larger galaxies.
Elena Asencio, Head of Studies and PhD student, University of Bonn
When the gravity of one body presses unevenly on certain parts of another, tides occur. These are similar to the tides that form on Earth due to the moon’s gravitational pull, which is stronger on the moon-facing side of the earth.
Dwarf galaxies are abundant in the Fornax cluster. Recent research shows that some of these dwarfs have an altered appearance, as if the cluster environment has disturbed them.
Such disturbances in the fornax dwarfs are not to be expected according to the standard model. Because, according to the Standard Model, the dark matter halos of these dwarfs should partially shield them from the tides stirred up by the cluster.
Pavel Kroupa, Professor, University of Bonn
Based on internal features and distance from the high-gravity cluster core, the authors calculated the predicted extent of the dwarfs’ disturbance. Large, low stellar mass galaxies and galaxies near the center of the cluster are more prone to disruption or disruption.
They compared the results to the level of clutter they found in images taken by the European Southern Observatory’s VLT Survey Telescope.
Asencio added: “The comparison showed that if one wants to explain the observations in the Standard Model, the fornax dwarfs should already be destroyed by gravity from the cluster center, even if the tides throwing them at a dwarf are 64 times weaker than your own Even the dwarf -Heaviness.”
Not only is this illogical, but it contradicts previous research that found that the external force needed to perturb a dwarf galaxy is the dwarf’s own gravity.
Contradiction to the standard model
The researchers concluded that the reported morphologies of fornax dwarfs could not be self-consistently explained by the mainstream paradigm. They ran the investigation again using Milgrom Dynamics (MOND).
The MOND theory proposes a Newtonian dynamics correction whereby gravity experiences an increase in the region of low accelerations, rather than assuming dark matter halos surrounding galaxies.
We were unsure whether the dwarf galaxies would be able to survive the extreme environment of a galaxy cluster in MOND due to the lack of protective dark matter halos in this model, but our results show remarkable agreement between the observations and the MOND Expectations for Fornax Dwarf Disturbance Levels.
dr Indranil Banik, University of St Andrews
Aku Venhola, one of the study’s co-authors and collaborator at the University of Oulu (Finland), and Steffen Mieske from the European Southern Observatory explained: “It is exciting to see that the data we obtained with the VLT survey telescope enabled such a thorough test of cosmological models.”
This is not the first time that a study examining the influence of dark matter on the dynamics and evolution of galaxies has concluded that data can best be explained when no dark matter is present in the vicinity of the galaxies .
“The number of publications showing incompatibilities between observations and the dark matter paradigm is increasing every year. It’s time to invest more resources in more promising theories‘ added Kroupa.
In addition, Pavel Kroupa is part of the transdisciplinary research areas “Modeling” and “Matter” at the University of Bonn.
Our results have major implications for fundamental physics. We expect to find more troubled dwarves in other clusters, a prediction for other teams to check.
dr Hongsheng Zhao, University of St Andrews
Participating institutions and funding:
In addition to the University of Bonn (Czech Republic), the European Southern Observatory (ESO), the University of Oulu (Finland) and Charles University in Prague were also involved in the study. The study was funded by the German Academic Exchange Service, the UK Science and Technology Facilities Council and the University of Bonn.
Magazine reference:
Asencio, E. et al. (2022) The distribution and morphologies of the Fornax Cluster dwarf galaxies suggest that they lack dark matter. Monthly Bulletins of the Royal Astronomical Society. doi: 10.1093/mnras/stac1765
Source: https://www.uni-bonn.de/en
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