No dark matter halos

No dark matter halos

The dwarf galaxy NGC1427A flies by the Fornax galaxy cluster and undergoes turbulence that may not have been doable if this galaxy had been surrounded by a heavy, stretching darkish matter halo, as required by customary cosmology. Credit score: ESO

In line with the Commonplace Mannequin of cosmology, the overwhelming majority of galaxies are surrounded by a halo of darkish matter particles. This halo is invisible, however its mass exerts a powerful gravitational power on neighboring galaxies. A brand new examine by the College of Bonn (Germany) and the College of St Andrews (Scotland) challenges this view of the universe. The outcomes point out that dwarf galaxies within the second closest galaxy cluster to Earth – referred to as the Fornax Cluster – are devoid of darkish matter halos. The examine appeared within the journal Month-to-month Notices of the Royal Astronomical Society.

Dwarf galaxies are small, faint galaxies that may normally be present in galaxy clusters or close to bigger galaxies. For that reason, they could be affected by the gravitational results of their bigger companions. “We current an revolutionary solution to check the Commonplace Mannequin primarily based on how a lot dwarf galaxies are disturbed by gravity and tides from bigger neighboring galaxies,” stated Elena Ascencio, Ph.D. Scholar on the College of Bonn and lead writer of the story. Tides come up when the gravity of 1 object in a different way pulls totally different elements of one other object. These are much like Earth’s tides, which come up as a result of the Moon is pulling extra strongly on the facet of the Earth that faces the Moon.

The Fornax Cluster incorporates numerous dwarf galaxies. Latest observations present that a few of these dwarfs seem deformed, as if disturbed by the cluster atmosphere. “Such disturbances in Fornax dwarfs are usually not anticipated in keeping with the usual mannequin,” stated Pavel Krupa, a professor on the College of Bonn and Charles College in Prague. “It is because, in keeping with the Commonplace Mannequin, the darkish matter halos of those dwarfs ought to partially protect them from the tides stirred up by the mass.”

The authors analyzed the anticipated stage of turbulence of the dwarfs, which will depend on their inside traits and their distance from the gravitationally sturdy cluster middle. Galaxies of enormous however low-mass stellar plenty and galaxies near the middle of the cluster are simple to disturb or destroy. They in contrast the outcomes to the extent of perceived turbulence evident from pictures taken with the European Southern Observatory’s VLT Survey Telescope.

“The comparability confirmed that if one desires to clarify observations within the Commonplace Mannequin, Fornax dwarfs should certainly be destroyed by gravity from the middle of mass even when the tides they elevate on a dwarf are sixty-four instances weaker than the dwarf’s self-gravity,” says Elena Asencio. Not solely is that this counter-intuitive, she stated, it additionally contradicts earlier research, which have discovered that the exterior power wanted to perturb a dwarf galaxy is roughly the identical because the dwarf’s self-gravity.

Contradiction with the Commonplace Mannequin

From this, the authors conclude that, within the Commonplace Mannequin, the noticed morphology of Fornax dwarfs can’t be defined in a self-consistent method. They repeated the evaluation utilizing Milgromian dynamics (MOND). Relatively than assuming darkish matter halos surrounding galaxies, MOND idea proposes a correction for Newtonian dynamics during which gravity experiences a lift within the low acceleration regime.

“We weren’t positive that dwarf galaxies would be capable of survive within the harsh atmosphere of the MOND galaxy cluster, because of the absence of protecting darkish matter halos on this mannequin,” stated Dr. Indranel Panik from the College of St Andrews. “However our outcomes present a exceptional settlement between the observations and MOND predictions for the extent of Fornax dwarf disturbance.”

stated Akko Venhola of the College of Oulu (Finland) and Stephen Miski of the European Southern Observatory, who’re co-authors of the examine.

This isn’t the primary time {that a} examine inspecting the impact of darkish matter on the dynamics and evolution of galaxies has concluded that observations are greatest defined when they aren’t surrounded by darkish matter. “The variety of publications displaying the incompatibility between observations and the darkish matter mannequin is rising yearly. It’s time to begin investing extra assets in additional promising theories,” stated Pavel Krupa, a member of the College’s Modeling of Interdisciplinary and Matter Analysis Fields. Bonn.

Dr Hongsheng Zhao of the College of St Andrews added, “Their outcomes have main implications for primary physics. We anticipate finding extra perturbed dwarfs in different teams, a prediction that different groups ought to confirm.”


A brand new rotation within the galaxy preserves the controversial idea of gravity


extra data:
Elena Asencio et al, The distribution and formations of the dwarf Fornax Cluster galaxies point out that they lack darkish matter, Month-to-month Notices of the Royal Astronomical Society (2022). DOI: 10.1093/mnras/stac1765

Offered by the College of Bonn

the quote: No hint of darkish matter halos (2022, August 5) Retrieved August 5, 2022 from https://phys.org/information/2022-08-dark-halos.html

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