Cosmology with Modified Newtonian Dynamics (MOND)

Abstract

It is well-known that the application of Newtonian dynamics to an expanding spherical region leads to the correct relativistic expression (the Friedmann equation) for the evolution of the cosmic scale factor. Here, the cosmological implications of Milgrom's modified Newtonian dynamics (MOND) are considered by means of a similar procedure. Earlier work by Felten demonstrated that in a region dominated by modified dynamics, the expansion cannot be uniform (separations cannot be expressed in terms of a scale factor) and that any such region will eventually re-collapse regardless of the initial expansion velocity and mean density. Here I show that, because of the acceleration threshold for the MOND phenomenology, a region dominated by MOND will have a finite size which, in the early Universe ($z>3$), is smaller than the horizon scale. Therefore, uniform expansion and homogeneity on horizon scale are consistent with MOND-dominated non-uniform expansion and the development of inhomogeneities on smaller scale. In the radiation-dominated era, the amplitude of MOND-induced inhomogeneities is much smaller than that implied by observations of the cosmic background radiation, and the thermal and dynamical history of the Universe is identical to that of the standard Big Bang. When matter first dominates the energy density of the Universe, the cosmology diverges from that of the standard model. Objects of galaxy mass are the first virialized objects to form (by z=10) and larger structure develops rapidly. At the present epoch, the Universe would be inhomogeneous out to a substantial fraction of the Hubble radius.

20 pages, LaTex (aaspp4.sty), 4 figures, submitted MNRAS

Cited by in corpus (58)

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• Modified Newtonian Dynamics (MOND): Observational Phenomenology and Relativistic Extensions
• Modified Newtonian Dynamics as an Alternative to Dark Matter
• DGP Specteroscopy
• Resolving the virial discrepancy in clusters of galaxies with modified Newtonian dynamics
• Testing Modified Newtonian Dynamics with Low Surface Brightness Galaxies --Rotation curve fits-
• From galactic bars to the Hubble tension: weighing up the astrophysical evidence for Milgromian gravity
• A Tale of Two Paradigms: the Mutual Incommensurability of LCDM and MOND
• Dynamical Friction on Star Clusters near the Galactic Center
• The KBC void and Hubble tension contradict $\Lambda$CDM on a Gpc scale $-$ Milgromian dynamics as a possible solution
• Dynamical Friction of Galactic Center Star Clusters with an Intermediate-Mass Black Hole
• A massive blow for $\Lambda$CDM $-$ the high redshift, mass, and collision velocity of the interacting galaxy cluster El Gordo contradicts concordance cosmology
• Modified Newtonian Dynamics of Large Scale Structure
• Distinguishing Between CDM and MOND: Predictions for the Microwave Background
• BOOMERanG Data Suggest a Purely Baryonic Universe
• The formation of cosmic structure with modified Newtonian dynamics
• The abundance of galaxy clusters in MOND: Cosmological simulations with massive neutrinos
• Constraints on the long-range properties of gravity from weak gravitational lensing
• The collision velocity of the bullet cluster in conventional and modified dynamics
• Confrontation of MOND Predictions with WMAP First Year Data
• Forming Galaxies with MOND
• Gravitational lensing in modified Newtonian dynamics
• Jeans analysis in modified gravity
• Reconciling MOND and dark matter?
• Stability of Anisotropic Stellar Filaments
• The formation of exponential disk galaxies in MOND
• 3D hydrodynamic simulations for the formation of the Local Group satellite planes
• The global stability of M33 in MOND
• Galaxy Cluster Bulk Flows and Collision Velocities in QUMOND
• Observing braneworld black holes
• Alternative ideas in cosmology
• Challenges for Lambda-CDM and MOND
• Methodological Reflections on the MOND/Dark Matter Debate
• The candidate cluster and protocluster catalog (CCPC) of spectroscopically identified structures spanning $2.74<z<3.71$
• Imprints of deviations from the gravitational inverse-square law on the power spectrum of mass fluctuations
• Hydrodynamical structure formation in Milgromian cosmology
• Nonhomogeneous Cooling, Entropic Gravity and MOND Theory
• The end of the Dark Ages in MOND
• The cosmological star formation history from the Local Cosmological Volume of galaxies and constraints on the matter homogeneity
• Spherical Collapse in Modified Newtonian Dynamics (MOND)
• Relaxation of N-body systems with additive r^-α interparticle forces
• Strong Hydrogen Absorption at Cosmic Dawn: the Signature of a Baryonic Universe
• Modeling the formation of galaxy clusters in MOND
• Predictions for the sky-averaged depth of the 21cm absorption signal at high redshift in cosmologies with and without non-baryonic cold dark matter
• Discord in Concordance Cosmology and Anomalously Massive Early Galaxies
• Thermodynamics of viscous Matter and Radiation in the Early Universe
• Testing Modified Gravity Theories with Numerical Solutions of the External Field Effect in Rotationally Supported Galaxies
• The formation of compact massive relic galaxies in MOND
• What if the universe expands linearly? A local general relativity to solve the "zero active mass" problem
• Cosmological Principle in Newtonian Dynamics
• Exact semianalytical calculation of rotation curves with Bekenstein-Milgrom nonrelativistic MOND
• Cosmological extrapolation of MOND
• The Effect of Cosmological Background Dynamics on the Spherical Collapse in MOND
• Consistent cosmological structure formation on all scales in relativistic extensions of MOND
• Self-Interactions in the Spacetime of a Scalar-Tensor Cosmic String
• Scaling relations of early-type galaxies in MOND
• Sub-mm gravity: confronting the modified dynamics with higher-dimensional theories
• Bimetric MOND as a framework for variable-$G$ theories -- local systems and cosmology