According to most physicists, the Standard Model of Cosmology depicts how the universe came into being. The evolution of galaxies within this model has now been analyzed by researchers, who discovered significant differences with actual findings.
The observed Universe is made up of a variety of galaxies, including ellipticals, spirals, lentriculars, and irregulars. In general, elliptical and lentricular galaxies are roundish, whereas spiral galaxies are very flat revolving disks that appear round face-on but have knife edges when viewed edge-on.
According to most physicists, the Standard Model of Cosmology depicts how the universe came into being. The evolution of galaxies within this model has now been researched by researchers at the University of Bonn, who discovered significant differences with actual data. The study also included researchers from the University of St. Andrews in Scotland and Charles University in the Czech Republic. The findings were just published in the Astrophysical Journal.
The majority of galaxies observable from Earth have a flat disk with a bulging center. As a result, they are identical to discus thrower sports equipment. However, according to the Standard Model of Cosmology, such disks should develop only infrequently. This is due to the fact that in the model, each galaxy is surrounded by a halo of dark matter. This halo is invisible, yet its bulk exerts a significant gravitational attraction on surrounding galaxies. “That’s why we keep witnessing galaxies merging in the model universe,” explains Prof. Dr. Pavel Kroupa of the University of Bonn’s Helmholtz Institute for Radiation and Nuclear Physics.
Here we discovered a huge disparity between forecast and reality; there appear to be substantially more flat disk galaxies than theory can explain.
Prof. Dr. Pavel Kroupa
The physicist adds that this crash has two effects: “First, the galaxies penetrate the process, breaking the disk shape. Second, it reduces the angular momentum of the new galaxy formed by the merger.” Simply said, this significantly reduces its spinning speed. The rotating motion generally ensures that the centrifugal forces occurring during this process cause a fresh disk to form. A new disk will not form if the angular momentum is sufficiently modest.
Large discrepancy between prediction and reality
Moritz Haslbauer, Kroupa’s doctoral student, led an international research group in the current project to analyze the evolution of the cosmos using the most recent supercomputer simulations. The calculations are based on the Standard Model of Cosmology, and they illustrate which galaxies should have formed by now if the theory is right. The researchers then compared their findings to what is currently believed to be the most accurate observational data of the real Universe visible from Earth.
“Here we discovered a huge disparity between forecast and reality,” Haslbauer adds, adding that “there appear to be substantially more flat disk galaxies than theory can explain.” However, even with today’s supercomputers, the resolution of the simulations is restricted. As a result, the number of disk galaxies that would arise under the Standard Model of Cosmology may have been overestimated. “However, even after accounting for this effect, there remains a significant gap between theory and reality that cannot be bridged,” Haslbauer says.
The scenario is different for an alternative to the Standard Model that does not include dark matter. According to the MOND theory (the acronym stands for “MilgrOmiaN Dynamics), galaxies do not develop by merging with one another. Instead, they are created by revolving gas clouds that get increasingly condensed. In a MOND universe, galaxies develop by absorbing gas from their surroundings. Mergers of fully formed galaxies, on the other hand, are uncommon in MOND. “Our research group in Bonn and Prague has established the methods to make calculations in this alternative theory uniquely,” says Kroupa, who is also a member of the University of Bonn’s Transdisciplinary Research Units “Modelling” and “Matter.” ” MOND’s forecasts match what we see.
Challenge for the Standard Model
Even with MOND, the precise mechanisms of galaxy growth are not entirely known. Furthermore, in MOND, Newton’s laws of gravity do not apply in some situations and must be replaced by the correct ones. This would have far-reaching implications in other areas of physics. “However, despite being originally created to address galaxies solely, the MOND theory addresses all known extragalactic cosmological problems,” explains Dr. Indranil Banik, who was engaged in this research. “Our study demonstrates that today’s young physicists still have the opportunity to make significant contributions to fundamental physics,” Kroupa adds.
