Constraints on exotic matter needed for an emergent universe

We study a composition of normal and exotic matter which is required for a flat emergent universe scenario permitted by the equation of state (EOS) (p = A - B1/2) and predict the range of the permissible values for the parameters A and B to explore a physically viable cosmological model. The permitted values of the parameters are determined taking into account the H(z)- z data obtained from observations, a model-independent Baryon Acoustic Oscillation (BAO) peak parameter and cosmic microwave background shift parameter (WMAP7 data). It is found that although A can be very close to zero, most of the observations favours a small and negative A. As a consequence, the effective EOS parameter for this class of emergent universe solutions remains negative always. We also compared the magnitude [mu (z)] versus redshift (z) curve obtained in the model with that obtained from the union compilation data. According to our analysis the class of emergent universe solutions considered here is not ruled out by the observations.