Genesis of cosmological tracker fields

The role of the quintessence field as a probable candidate for the repulsive dark energy, the conditions for tracking and the requisites for tracker fields are examined. The concept of “integrated tracking” is introduced and a new criterion for the existence of tracker potentials is derived assuming monotonic increase in the scalar energy density parameter Ω_φ with the evolution of the universe as suggested by the astrophysical constraints. It provides a technique to investigate generic potentials of the tracker fields. The general properties of the tracker fields are discussed and their behavior with respect to the tracking parameter ε is analyzed. It is shown that the tracker fields around the limiting value ε≃2/3 give the best fit with the observational constraints.