Constraining slow-roll inflation in the presence of dynamical dark energy

Jun-Qing Xia,Xinmin Zhang

doi:10.1016/j.physletb.2008.01.010

Jun-Qing Xia, Xinmin Zhang

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https://doi.org/10.1016/j.physletb.2008.01.010

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Journal: Physics Letters B	Publication Date: Jan 15, 2008
Citations: 5	License type: cc-by

Affiliation: Institute of High Energy Physics

Abstract

In this Letter we perform a global analysis of the constraints on the inflationary parameters in the presence of dynamical dark energy models from the current observations, including the three-year Wilkinson Microwave Anisotropy Probe (WMAP3) data, Boomerang-2K2, CBI, VSA, ACBAR, SDSS LRG, 2dFGRS and ESSENCE (192 sample). We use the analytic description of the inflationary power spectra in terms of the horizon-flow parameters {ϵi}. With the first order approximation in the slow-roll expansion, we find that the constraints on the horizon-flow parameters are ϵ1<0.014 (95% C.L.) and ϵ2=0.034±0.024 (1σ) in the ΛCDM model. In the framework of dynamical dark energy models, the constraints become obviously weak, ϵ1<0.022 (95% C.L.) and ϵ2=−0.006±0.039 (1σ), and the inflation models with a “blue” tilt, which are excluded about 2σ in the ΛCDM model, are allowed now. With the second order approximation, the constraints on the horizon-flow parameters are significantly relaxed further. If considering the non-zero ϵ3, the large running of the scalar spectral index is found for the ΛCDM model, as well as the dynamical dark energy models.

Highlights

Inflation in the very early universe is the most attractive paradigm, which is driven by a potential energy of a scalar field called inflaton and its quantum fluctuations turn out to be the primordial density fluctuations which seed the observed large scale structures (LSS) and the anisotropies of cosmic microwave background radiation (CMB)
Shown together are the corresponding reduction of χ2min values compared with the ΛCDM model
In this paper we perform an analysis of global fitting on the inflationary parameters in terms of the Horizon-flow parameters {ǫi} in the presence of dynamical dark energy models from the current observations

Summary

Introduction

Inflation in the very early universe is the most attractive paradigm, which is driven by a potential energy of a scalar field called inflaton and its quantum fluctuations turn out to be the primordial density fluctuations which seed the observed large scale structures (LSS) and the anisotropies of cosmic microwave background radiation (CMB). The current cosmological observations are in good agreement with an adiabatic and scale invariant primordial spectrum, which is consistent with single field slow-roll inflation predictions. The simplest candidate of dark energy is the cosmological constant (CC) it suffers from the fine-tuning and coincidence problems [3]. To ameliorate these dilemmas some dynamical dark energy models such as Quintessence [4], Phantom [5] and K-essence [6]. There exists some hints that the EoS of dark energy has crossed over −1 at least once from current astronomical observations [7, 8], namely Quintom dark energy model, which greatly challenges the above mentioned dark energy models

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Conclusion