Modified Gravity and the Phantom of Dark Matter

Abstract

Astrophysical data analysis of the weak-field predictions support the claim that modified gravity (MOG) theories provide a self-consistent, scale-invariant, universal description of galaxy rotation curves, without the need of non-baryonic dark matter. Comparison to the predictions of Milgrom's modified dynamics (MOND) provide a best-fit and experimentally determined universal value of the MOND acceleration parameter. The predictions of the modified gravity theories are compared to the predictions of cold non-baryonic dark matter (CDM), including a constant density core-modified fitting formula, which produces excellent fits to galaxy rotation curves including the low surface brightness and dwarf galaxies. Upon analysing the mass profiles of clusters of galaxies inferred from X-ray luminosity measurements, from the smallest nearby clusters to the largest of the clusters of galaxies, it is shown that while MOG provides consistent fits, MOND does not fit the observed shape of cluster mass profiles for any value of the MOND acceleration parameter. Comparison to the predictions of CDM confirm that whereas the Navarro-Frenk-White (NFW) fitting formula does not fit the observed shape of galaxy cluster mass profiles, the core-modified dark matter fitting formula provides excellent best-fits, supporting the hypothesis that baryons are dynamically important in the distribution of dark matter halos.

Ph.D. Thesis. 251 pages, 22 figures, 17 tables

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Cited by in corpus (13)

• The Dark Matter Profiles in the Milky Way
• Consequences of energy conservation violation: Late time solutions of $\Lambda (T)CDM$ subclass of $f(R,T)$ gravity using dynamical system approach
• Applying MOG to lensing: Einstein rings, Abell 520 and the Bullet Cluster
• Fourth Order Gravity, Scalar-Tensor-Vector Gravity, and Galaxy Rotation Curves
• Comparing the dark matter models, modified Newtonian dynamics and modified gravity in accounting for the galaxy rotation curves
• Modified Gravity or Dark Matter?
• Gravitational energy as dark energy: Cosmic structure and apparent acceleration
• New Constraints on Decaying Dark Matter from INTEGRAL/SPI
• Constraints on fourth order gravity from binary pulsar and gravitational waves
• Method of N-body simulation on the MOdified Gravity
• The Weak Lensing Mass of Cosmic Web Filaments and Modified Gravity (MOG)
• A comprehensive analysis using 9 dark matter halo models on the spiral galaxy NGC 4321
• Estimation of xi parameter on the Moffat Gravity