Testing Cosmologies with Dark Sector Interaction Using Redshift Space Distortion Data
Cosmology, Alternative Model, Dark Sector, Disturbance Theory, Growth Rate, Redshift Space Distortion.
Here we use the Chaplygin gas model decomposed in matter without pressure and vacuum energy to study the distortion in redshift space caused by the peculiar velocity of galaxies. Introducing baryonic matter into the equations that describe dynamics, we get the theoretical prediction of the fσ8 combination and show that its evolution depends on the vacuum energy density clustering model. Using the observational data for the redshift space distortion measurements fσ8, we performed a statistical test using the Monte Carlo Chain operating the Python MultiNest algorithm. Assuming that the vacuum density is homogeneous we find the best fit parameter set σ8(0) = 0.80 {+0.14 −0.11}, Ωm0 = {0.31+0.19 −0.17} and α = −0.05 {+0.64 −0.58}. By setting some values for the α parameter we find that such models are able to describe fσ8 data with the best fit Ωm0−σ8(0) growing to α < 0 and descending to α > 0.