Scalar Field Dark Matter

Abstract

The main goal of this work is to put the last results of the Scalar Field Dark Matter model of the Universe at cosmological and at galactic level in a work together. We present the complete solution to the 95% scalar field cosmological model in which the dark matter is modeled by a scalar field Φ with the scalar potential $V(\Phi ) = V_o [\cosh (\lambda \sqrt {k_o } \Phi ) - 1]$ and the dark energy is modeled by a scalar field Ψ, endowed with the scalar potential $\tilde V(\Psi ) = \tilde V_o [\sinh (\alpha \sqrt {k_o } \Psi )]^\beta$. This model has only two free parameters, λ and the equation of state ωψ. The results of the model are: 1) the fine tuning and the cosmic coincidence problems are ameliorated for both dark matter and dark energy and the models agrees with astronomical observations. 2) The model predicts a suppression of the Mass Power Spectrum for small scales having a wave number k>k _min,φ, where k _min,φ ≃4.5h Mpc ⁻¹ for λ≃20.3. This last fact could help to explain the dearth of dwarf galaxies and the smoothness of galaxy core halos. 3) From this, all parameters of the scalar dark matter potential are completely determined. 4) The dark matter consists of an ultra-light particle, whose mass is m _φ ≃1.1×10 ⁻²³ eV and all the success of the standard cold dark matter model is recovered. 5) If the scale of renormalization of the model is of order of the Planck Mass, then the scalar field Φ can be a reliable model for dark matter in galaxies. 6) The predicted scattering cross section fits the value required for self-interacting dark matter. 7) Studying a spherically symmetric fluctuation of the scalar field Φ in cosmos we show that it could be the halo dark matter in galaxies. 8) The local space-time of the fluctuation of the scalar field Φ contains a three dimensional space-like hypersurface with surplus of angle. 9) We also present a model for the dark matter in the halos of spiral galaxies, we obtain that 10) the effective energy density goes like 1/(r ² +K ²) and 11) the resulting circular velocity profile of tests particles is in good agreement with the observed one in spiral galaxies. This implies that a scalar field could also be a good candidate as the dark matter of the Universe