Quintom Cosmology: Theoretical implications and observations

Understand

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 constant boundary is mildly favored, although the data are still far from being conclusive.
• As a theoretical setup we introduce a no-go theorem existing in quintom cosmology, and based on it we discuss the conditions for the equation of state of dark energy realizing the quintom scenario.
• The simplest quintom model can be achieved by introducing two scalar fields with one being quintessence and the other phantom.