New MOND theory able to account for cosmic microwave background

The linear MPS (k) for models that are excellently matched to Sloan Digital Sky Survey data release 7 (DR7) luminous-red galaxies. (LRG). [105]. A bias parameter b is also included. You will notice that the Hubble constant (derived) for each model is not the same. Credit: DOI: 10.1103/PhysRevLett.127.161302
Czech Academy of Sciences researchers have been shaking up the Astrophysics community with their modified Newtonian dynamics theory (MOND). This theory, which is not based on dark matter but backs up theories that claim there may be a type of gravity that could be responsible for the attributes observed in the cosmic microwave background. Their ideas were described in a paper published by Tom Zlosnik and Constantinos Skordis in Physical Review Letters.

Many in the astrophysics community have been using the concept of dark matter for many years to explain phenomena that cannot be explained in traditional ways. Gravitational lensing or measurements of gravitational wave speeds found in the CMB are two examples. Some have been reluctant to accept dark matter due to the lack of physical evidence. Others have suggested that dark matter might actually be a form of gravity that could explain these observations. However, these MOND theories are not able to account for features in the CMB. Skordis, Zlosnik claim that they have created a MOND model which accounts for these data and still includes gravitational lensing.

The original MOND idea of two types fields that act together as a type gravitational forceone is vector-based and the other is scalar. This new model starts with the original MOND idea. The researchers then added parameters to suggest gravity-modifying fields that were created in the early universe. These fields mimicked dark matter. They also suggest that these fields evolved over time to become the type of force described in the original MOND model.

Skordis, Zlosnik believe their model can be used for both gravitational lensing as well as data in the CMB. They plan to investigate if the model can explain the universe's abundance of lithium and discrepancies between measurements of the cosmic growth rate, something dark matter theories have failed. Their ideas also have no ghost instabilities, they say.

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More information: Constantinos Skordis and colleagues, New Relativistic Theory for Modified Newtonian Dynamics. Physical Review Letters (2021). Information for the Journal: Physical Review Letters Constantinos Skordis and colleagues, New Relativistic Theory For Modified Newtonian Dynamics, (2021). DOI: 10.1103/PhysRevLett.127.161302

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