no trace of dark matter halo

no trace of dark matter halo

The dwarf galaxy NGC1427A flies through the Fornax galaxy cluster and undergoes disturbances that would not be possible if this galaxy were surrounded by a massive and expanding dark matter halo, as required by standard cosmology. credit: ESO

According to the Standard Model of cosmology, 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 the surrounding galaxies. A new study led by the University of Bonn (Germany) and the University of St Andrews (Scotland) challenges this view of the universe. The results suggest that the dwarf galaxies of the second closest galaxy cluster to Earth – known as the Fornax Cluster – are free of such dark matter halos. The study appeared in the journal Monthly Notice of the Royal Astronomical Society,

Dwarf galaxies are smaller, fainter galaxies commonly found in galaxy cluster Or near larger galaxies. Because of this, they can be affected by the gravitational effects of their larger companions. “We present an innovative way of testing standard model “How many dwarf galaxies are troubled by the gravity, tidal waves of nearby large galaxies,” said Elena Asencio, PhD student at the University of Bonn and lead author of the story. Tides arise when the gravitational pull from one body exerts a different force on different parts of the other body. These are similar to tides on Earth, which arise because the Moon pulls more strongly on the side of the Earth that faces the Moon.

The Fornax Cluster contains a rich population of dwarf galaxies. Recent observations suggest that some of these dwarfs appear distorted, as if they have been disturbed by cluster atmosphere. “Such disturbances in the fornax dwarfs are not expected according to the Standard Model,” said Professor Pavel Krupa from the University of Bonn and Charles University in Prague. “This is because, according to the standard patternThe dark matter halos These dwarfs should partially shield them from the tides picked up by the cluster.”

The authors analyzed the dwarfs’ expected level of turbulence, which depends on their intrinsic properties and their distance from the gravitationally powerful cluster center. Galaxies with larger sizes but less stellar mass and closer to the cluster center are more easily perturbed or destroyed. They compared the results to their observed level of apparent turbulence from photographs taken by the European Southern Observatory’s VLT survey telescope.

Elena Asencio states that “the comparison showed that, if one wishes to interpret the observations in the Standard Model. The Fornax dwarfs must have already been destroyed by gravity from the cluster center, even though the tides rising on the dwarf be sixty-four times weaker than the dwarf’s own self-gravity.” Not only is this counter-intuitive, she said, it also contradicts previous studies, which found that the external force required to perturb a dwarf galaxy is similar to the dwarf’s self-gravity.

Unlike the standard model

From this, the authors concluded that, in the Standard Model, it is not possible to explain the observed morphology of fornax dwarfs in a self-consistent way. They repeated the analysis using Milgromian dynamics (MOND). Rather than assuming dark matter halos surrounding galaxies, the MOND theory proposes an improvement in Newtonian dynamics by which gravity experiences an increase in the regime of low acceleration.

“We weren’t sure dwarf galaxies Because of the absence of the protective dark matter halo in this model, a galaxy in MOND would be able to survive in the cluster’s extreme environment,” said Dr. Indranil Banik of the University of St. Andrews. “But our results show a remarkable agreement between Observations and MOND expectations for the level of disturbance of the Fornax dwarfs.”

“It is exciting to see that the data we have obtained with the VLT survey telescope allows such an in-depth test of the cosmological model,” said Aku Venhola from the University of Oulu (Finland) and Stefan Miske from the European Southern Observatory. Said, co-author of The Study.

This is not the first time that a study has tested the effect of dark matter on the dynamics and evolution of galaxies concluded that the observations are better explained when they are not surrounded by dark matter. “The number of publications showing the inconsistency between the observation and the dark matter paradigm continues to grow every year. It is time to start investing more resources into more promising theories,” said Pavel Krupa, member of the Transdisciplinary Research Area Modeling and Modeling. Case at the University of Bonn.

Dr. Hongsheng Zhao of the University of St. Andrews said that their “results have major implications for fundamental physics. We expect to find more perturbed dwarfs in other groups, a prediction that other teams must verify.”


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more information:
Elena Asencio et al, Fornax Cluster The distribution and morphology of dwarf galaxies suggest they lack dark matter, Monthly Notice of the Royal Astronomical Society (2022). DOI: 10.1093/mnras/stac1765

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Citation: No trace of dark matter halos (2022, August 5), retrieved from https://phys.org/news/2022-08-dark-halos.html on August 5, 2022

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