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      A Modified Dynamical Model of Cosmology

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          Abstract

          A modified dynamical model of cosmology is derived based on imposing Neumann boundary condition on cosmological perturbation equations. Then, it is shown that a new term appears in the equation of motion which leads to a modified Poisson equation with a new density term. In addition, a modified Hubble parameter due to the presence of this new density term is derived. Moreover, it is proved that, without a cosmological constant, such model has a late time accelerated expansion with an equation of state converging to w<-1. Also, the luminosity distance in the present model is shown to differ from that of the LCDM model at high red shifts. Furthermore, it is found that the adiabatic sound speed squared is positive in radiation dominated era and then converges to zero at later times. We bound the parameters of the model based on Type Ia Supernovae, Hubble parameter data and the age of the oldest stars. Theoretical implications of Neumann boundary condition has been discussed and it is shown that by fixing the value of the conjugate momentum(under certain conditions), one could derive our version of modified dynamics.

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          A new era in the search for dark matter

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            The failures of the standard model of cosmology require a new paradigm

            Cosmological models that invoke warm or cold dark matter can not explain observed regularities in the properties of dwarf galaxies, their highly anisotropic spatial distributions, nor the correlation between observed mass discrepancies and acceleration. These problems with the standard model of cosmology have deep implications, in particular in combination with the observation that the data are excellently described by Modified Newtonian Dynamics (MOND). MOND is a classical dynamics theory which explains the mass discrepancies in galactic systems, and in the universe at large, without invoking dark entities. MOND introduces a new universal constant of nature with the dimensions of acceleration, a0, such that the pre-MONDian dynamics is valid for accelerations a >> a0, and the deep MONDian regime is obtained for a << a0, where space-time scale invariance is invoked. Remaining challenges for MOND are (i) explaining fully the observed mass discrepancies in galaxy clusters, and (ii) the development of a relativistic theory of MOND that will satisfactorily account for cosmology. The universal constant a0 turns out to have an intriguing connection with cosmology: \bar a0 == 2 pi a0 \approx c H_0 \approx c^2(Lambda/3)^{1/2}. This may point to a deep connection between cosmology and internal dynamics of local systems.
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              Motion of particles in solar and galactic systems by using Neumann boundary condition

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                Author and article information

                Journal
                11 October 2018
                Article
                1810.05001
                c6ef0b79-ea3a-4284-b4da-f9bb3b98c9fa

                http://arxiv.org/licenses/nonexclusive-distrib/1.0/

                History
                Custom metadata
                83F05, 83D05
                26 pages, 14 figures and 2 tables
                gr-qc

                General relativity & Quantum cosmology
                General relativity & Quantum cosmology

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