General parametrization for energy density of quintessence field

Understand

We present a general parametrization for energy density of a quintessence field, a minimally coupled canonical scalar field which rolls down slowly during the late time.

• This parametrization can mimic all classes of quintessence dynamics, namely scaling-freezing, tracker and thawing dynamics for any redshift.
• For thawing dynamics the parametrization needs two free parameters while for scaling-freezing and tracker dynamics it needs at least four free parameters.
• More parameters make the model less interesting from the observational data analysis point of view but as we expect more precise data in future it may be possible to constrain the models with multiple free parameters which can tell about the dynamics more precisely.