Abstract
Non-canonical scalar fields with the Lagrangian {{mathcal {L}}} = X^alpha - V(phi ), possess the attractive property that the speed of sound, c_s^{2} = (2,alpha - 1)^{-1}, can be exceedingly small for large values of alpha . This allows a non-canonical field to cluster and behave like warm/cold dark matter on small scales. We derive a general condition on the potential in order to facilitate the kinetic term X^alpha to play the role of dark matter, while the potential term V(phi ) playing the role of dark energy at late times. We demonstrate that simple potentials including V= V_0coth ^2{phi } and a Starobinsky-type potential can unify dark matter and dark energy. Cascading dark energy, in which the potential cascades to lower values in a series of discrete steps, can also work as a unified model.
Highlights
A key feature of our universe is that 96% of its matter content is weakly interacting and non-baryonic
It is widely believed that this so-called dark sector consists of two distinct subcomponents, the first of which, dark matter (DM), consists of a pressureless fluid which clusters, while the second, dark energy (DE), has large negative pressure and causes the universe to accelerate at late times
For the coth potential wV behaves like a scaling solution only at early times and drops to wV −1 at z ∼ 104. For both potentials the equation of state (EOS) of the kinetic term stays pegged at wX = 0, allowing it to play the role of dark matter unified models of the dark sector
Summary
A key feature of our universe is that 96% of its matter content is weakly interacting and non-baryonic. It is widely believed that this so-called dark sector consists of two distinct subcomponents, the first of which, dark matter (DM), consists of a pressureless fluid which clusters, while the second, dark energy (DE), has large negative pressure and causes the universe to accelerate at late times. The fine tuning problem associated with Λ and the cosmic coincidence issue, have motivated the development of dynamical dark energy (DDE) models in which the DE density and equation of state (EOS) evolve with time [9,10,11,12,13,14,15,16]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
