Accelerated Expansion and Structure Formation with a Single Scalar Field

ABSTRACT

In this work we calculate and simulate the different ingredients needed to obtain the matter density profile of the large-scale structure we observe now days in a qualitative way. This work begins assuming that the seeds of the early universe were small fluctuations that lived inside a homogeneous FLRW background, and which are studied using the Linear Perturbation Theory, these fluctuations then grew because of gravitational instability, in this way giving birth to what we see today: galaxies, clusters of galaxies, etc. The key difference of this work compared with other works lays in the fact that we introduce Φ² as a scalar field candidate to dark matter, and as one of the main ingredients needed to obtain the large-scale structure we see today. We then solve the obtained set of equations like a dynamical system in which we introduce new dimensionless parameters that describe the cosmology of the different studied quantities, this shows us that both; the gravitational potential and the fluctuations on the scalar field are the main ingredients to the spectrum of the density contrast, the last one being responsable of the description of matter distribution we observe these days. Also, we have developed the non linear regime with the sphericall collapse formalism in order to compute the parameters of virialized structure with our hypothesis. Finally, we show how the quantum effects of the same scalar field can explain the value of the cosmological constant.

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