Cosmic expansion with curved dark energy cosmology: Inevitability of cosmic doomsday

摘要

In this work, we have constructed deceleration-acceleration and future evolution of cosmic expansion with curved dynamical dark energy models. Closed and open spatial curvatures are calculated by assuming that dark energy density does not exceed 85% of the closure density and by obtaining lower bounds on the ratio of dark energy to matter density, in terms of equation of state of dark energy. The range of transition epoch z(t) approximate to (0.55 - 0.8) realized for spatial curvature -0.1 < Omega(k(0)) < 0.1 is consistent with model independent estimations coming from galactic ages, strong lensing, Type Ia supernovae and recent constraints coming from H-0 measurements in non-flat dynamical dark energy models. Two novel parametrizations of dark energy equation of state namely the logarithmic and oscillatory, which are singularity free at future point z -> -1 are used to study the deceleration parameter q(z). Irrespective of spatial curvature, cosmic doomsday has been found inevitable for both the parametrizations. The time evolution of logarithmic parametrization, being reminiscent of a quintom field (canonical+phantom), is converted into dynamics of a canonical quintessence and a phantom field for the redshift range (z(t),z approximate to 10) and (zt, z -> -1). It is found that irrespective of spatial curvature, the quintessence component becomes sub-dominant in future giving it's way to the phantom component.