Observational constraints on modified Chaplygin gas in Horavaa€“Lifshitz gravity with dark radiation

摘要

Cosmological models with modified Chaplygin gas (MCG) in the framework of Horavaa€“Lifshitz (HL) theory of gravity, both with and without detailed balance, are obtained. The equation of state (EOS) for a MCG contains three unknown parameters namely, e??′, e???, e??μ. The allowed values of some of these parameters of the EOS are determined using the recent astrophysical and cosmological observational data. Using observational data from $H(z)-z$, baryon acoustic oscillation (BAO) peak parameter and cosmic microwave background (CMB) shift parameter we study cosmologies in detailed-balance and beyond detailed-balance scenario. In this paper we take up the beyond detailed-balance scenario in totality and contribution of dark radiation in detailedbalance scenario on the parameters of the EOS. We explore the effect of dark radiation on the whole range of the effective neutrino parameter ($e??￥ N_{e???}$) to constrain matter contributing parameter e??μ in both the detailed-balance and the beyond detailed-balance scenarios. It has been observed that greater the dark radiation less the matter contribution in the MCG in both the scenario considered here. In order to check the validity of beyond detailed-balance scenario we plot supernovae magnitudes (e???) with red-shift of Union2 data and then the variation of state parameter with redshift is studied. It is noted that beyond detailed-balance scenario is suitable for cosmological model in HL gravity with MCG.