Barboza-Alcaniz Equation of State Parametrization : Constraining the Parameters in Different Gravity Theories

Abstract

To justify the twenty years old distant Ia Supernova observations which revealed to us that our universe is experiencing a late time cosmic acceleration, propositions of existence of exotic fluids inside our universe are made. These fluids are assumed to occupy homogeneously the whole space of the universe and to exert negative pressure from inside such that the late time accelerated expansion is caused. Among the different suggested models of such exotic matters/ energy popularly coined as dark matter / dark energy, a well known and popular process is "introduction of redshift parametrization" of the equation of state parameter of these fluids. We, very particularly, take the parametrization proposed by Barboza and Alcaniz along with the cosmological constant. We use thirty nine data points for Hubble's parameter calculated for different redshifts and try to constrain the dark energy equation of state parameters for Barboza Alcaniz modelling. We then constrain the dark energy parametrization parameters in the background of Einstein's general relativity, loop quantum gravity and Horava Lifshitz gravity one after another. We find the 1$\sigma$, 2$\sigma$ and 3$\sigma$ confidence contours for all these cases and compare them with each other. We try to speculate which gravity is constraining the parameters most and which one is letting the parameters to stay within a larger domain. We tally our results of 557 points Union2 Sample and again compare them for different gravity theories.