Too Many Disk Galaxies Than Theory Allows
The Standard Model of Cosmology defines how the universe came into being according to the perspective of most physicists. Researchers at the University of Bonn have actually currently studied the evolution of galaxies within this model, finding considerable inconsistencies with real observations. The University of St. Andrews in Scotland and Charles University in the Czech Republic were likewise involved in the research study. The journal Astrophysical published the results.
The majority of galaxies visible from Earth resemble a flat disk with a thickened center. They are therefore similar to the sports equipment of a discus thrower. However, according to the Standard Model of Cosmology, such disks ought to form instead seldom. This is since every galaxy is bordered by a halo of dark matter in the model.
This halo is invisible yet puts in a strong gravitational pull on close-by galaxies due to its mass. “That is why we keep seeing galaxies merging in the model universe,” clarifies Prof. Dr. Pavel Kroupa of the Helmholtz Institute for Radiation and Nuclear Physics at the University of Bonn.
This collision has two outcomes. The physicist describes: “First, the galaxies infiltrate the process, destroying the disk shape. Second, it decreases the angular momentum of the brand-new galaxy created by the merger.” Simply put, this considerably decreases its rotational speed.
The spinning motion generally guarantees that the centrifugal forces acting throughout this process trigger a new disk to form. But, if the angular momentum is too small, a new disk will not form whatsoever.
A big discrepancy between prediction and reality
In the present research study, Kroupa’s doctoral student, Moritz Haslbauer, led an international research study team to inspect the universe’s evolution utilizing the latest supercomputer simulations. The calculations are based upon the Standard Model of Cosmology; they reveal which galaxies ought to have formed by today if this theory were correct. The scientists after that compared their results with what is presently most likely the most precise observational data of the real universe visible from Earth.
” Here we ran into a considerable disparity between prediction and reality,” Haslbauer claims: “There are seemingly substantially extra flat disk galaxies than can be described by theory.” The resolution of the simulations is limited even on today’s supercomputers. It may for that reason be that the number of disk galaxies that would form in the Standard Model of Cosmology has been ignored. “However, even if we consider this effect, there remains a severe distinction in between theory and observation that can not be remedied,” Haslbauer mentions.
The situation is different for a substitute to the Standard Model, which dispenses with dark matter. According to the supposed MOND theory (the acronym stands for “MilgrOmiaN Dynamics), galaxies do not expand by merging with each other. Rather, they are developed from revolving gas clouds that become more and more condensed.
In a MOND universe, galaxies likewise expand by consuming gas from their surroundings. Mergers of full-grown galaxies are rare in MOND. “Our research team in Bonn and Prague has distinctly developed the methods to do calculations in this alternative theory,” claims Kroupa, who is also a member of the Transdisciplinary Research Units “Modelling” and “Matter” at the University of Bonn. “MOND’s predictions are consistent with what we really see.”
Challenge for the Standard Model
However, the specific mechanisms of galaxy growth are not yet completely comprehended, even with MOND. Additionally, in MOND, Newton’s laws of gravity do not apply under certain conditions yet require to be changed by the right ones. This would certainly have far-ranging repercussions for other areas of physics. “Nevertheless, the MOND theory addresses all recognized extragalactic cosmological issues regardless of being originally formulated to address galaxies only,” claims Dr. Indranil Banik, that was involved in this research. “Our research study shows that young physicists today still can make considerable contributions to fundamental physics,” Kroupa adds.
Read the original article on Science Daily.
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Reference: Moritz Haslbauer, Indranil Banik, Pavel Kroupa, Nils Wittenburg, Behnam Javanmardi. The High Fraction of Thin Disk Galaxies Continues to Challenge ΛCDM Cosmology. The Astrophysical Journal, 2022; 925 (2): 183 DOI: 10.3847/1538-4357/ac46ac
