We review in detail a number of approaches that have been adopted to try and explain the
remarkable observation of our accelerating universe. In particular we discuss the arguments …

Recent cosmological observations suggest the existence of a positive cosmological constant
Λ with the magnitude Λ (Gℏ/c3)≈ 10− 123. This review discusses several aspects of the …

We review the paradigm of quintom cosmology. This scenario is motivated by the
observational indications that the equation-of-state of dark energy across the cosmological …

Taylor expanding the cosmological equation of state around the current epoch is the
simplest model one can consider that does not make any a priori restrictions on the nature of …

This review summarizes recent attempts to reconstruct the expansion history of the universe
and to probe the nature of dark energy. Reconstruction methods can be broadly classified …

I review the problem of dark energy focussing on cosmological constant as the candidate
and discuss what it tells us regarding the nature of gravity. Section 1 briefly overviews the …

The conceptual difficulties associated with a cosmological constant have led to the
investigation of alternative models in which the equation of state parameter, w= p/ρ, of the …

We propose a simple phenomenological parameterization of quintessence with a time-
varying equation of state. In particular, it accounts for the possibility of early dark energy. The …

In this work, we have developed an FLRW type model of a universe which displays transition
from deceleration in the past to the acceleration at the present. For this, we have considered …

The dark energy component of the Universe is often interpreted either in terms of a
cosmological constant or as a scalar field. A generic feature of the scalar field models is that …