Abstract
We present a Dark Energy (DE) model based on a scalar field with an inverse power law potential (IPL) V(∅)=M4+n∅−n. We consider three different models n=1/2, n=3/4 and n=1 and we vary the value of M and the initial amount of energy density Ω∅ at the scale factor ac. We obtain a time dependent equation of state (EoS) , with w∅=1/3 at early times for a scale factor ac with a steep transition to w∅=1 at , , , lasting a long period of time and a subsequent descent w∅=-1 to for to finally grow to w∅= -0.906, w∅=-0.932, w∅=-0.924 for n=1/2, n=3/4 and n=1 respectively. The values of M and Ω∅(ac) are M(eV)= 4.63,127.31,2465.46 and Ω∅(ac)=0.038,0.148,0.227 for n= 1/2, n= 3/4 and n=1 respectively. We show the differences in the evolution of H, the CMB and Matter power spectra, and the redshift space distortion (RSD)parameter. Precision cosmological data allow us to test the dynamics of Dark Energy and we obtain in all three cases a reduction of compared to ∧CDM with and an equivalent fit for CMB and SNIa data.
Highlights
It has passed almost twenty years since the accelerated expansion of the universe was first observed by distance measurements using type Ia supernovae (SNeIa) [1] [2]
This lack of understanding is commonly expressed in terms of the “fine-tuning” and the “coincidence” problems; the former asks why the observations set the value of the Dark Energy (DE) density ρΛ to almost 10120 orders of magnitude below conservative estimations based on quantum field theory, while the “coincidence” problem inquires why the energy densities of the DE and the matter are of the same order of magnitude precisely at present time
In this paper we study the constraints set by recent cosmological observations on a scalar field model with inverse power law (IPL) potential V = M 4+nφ −n giving a good fit to cosmological observations
Summary
It has passed almost twenty years since the accelerated expansion of the universe was first observed by distance measurements using type Ia supernovae (SNeIa) [1] [2]. The ΛCDM model has proved to agree very well with the observations [3], there is no understanding of the physical mechanism that determines the origin and the magnitude of the cosmological constant Λ and of why and when the universe accelerates [10] This lack of understanding is commonly expressed in terms of the “fine-tuning” and the “coincidence” problems; the former asks why the observations set the value of the DE density ρΛ to almost 10120 orders of magnitude below conservative estimations based on quantum field theory, while the “coincidence” problem inquires why the energy densities of the DE and the matter are of the same order of magnitude precisely at present time.
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