A new recipe for $\Lambda$CDM

Understand

It is well known that a canonical scalar field is able to describe either dark matter or dark energy but not both.

• We demonstrate that a non-canonical scalar field can describe both dark matter and dark energy within a unified setting.
• We consider the simplest extension of the canonical Lagrangian ${\cal L} \propto X^\alpha - V(\phi)$ where $\alpha \geq 1$ and $V$ is a sufficiently flat potential.
• In this case the kinetic term in the Lagrangian behaves just like a perfect fluid, whereas the potential term mimicks the cosmological constant.