Possible combinations of early and late time cosmologies through BAO scales.

The theoretical scenarios of early universe and late time accelerated expansion constitute an open problem in cosmology. Relative Baryon Acoustic Oscillation (BAO) scales measured by 6dFGS, S D S S + 2 d F G R S , BOSS DR11 Ly α and BOSS DR11 QSO Ly α are used to investigate the parameter spaces of combinations of pre-recombination physics and late time cosmology. For pre-recombination physics we fix N eff = 3 and 4 and incorporate an Early Dark Energy (EDE) component. For late time cosmologies we consider curved Λ CDM model, Dynamical Dark Energy (DDE) model with CPL parameterisation ( ω 0 , ω 1 ) of equation of state, Coupled Dark Energy (CDE) model with constant coupling and curved DGP brane-world scenario. Combination of a curved Λ CDM ( Ω k Λ CDM) model with N eff -EDE cosmology is found to be possible. For DDE, the relative BAO scales are achievable through ω 1 preferring the region ω 1 < 0 . For N eff -EDE-CDE, the BAO scales are generated for both dark energy-dark matter and dark matter-dark energy conversion, however with exceptionally large value of dark energy density parameter and constant equation of state with ω 0 > - 1 . Curved DGP cosmology ( Ω k DGP) is found to join with N eff -EDE cosmology through curvature parameter Ω k (0) ∈ [ - 0.002 , - 0.1 ] and cross-over parameter Ω r c ∈ [ 0.08 , 0.45 ] . Cosmic ages are calculated for the derived parameters of Ω k Λ CDM, flat DDE and Ω k DGP models and compared with the ages of few globular clusters available in literature. Curved cosmologies are found to be promising. [ABSTRACT FROM AUTHOR]