Searching for cosmological preferred axis using cosmographic approach

摘要

Recent released Planck data and other astronomical observations show that the universe may be anisotropic on large scales. This hints a cosmological privileged axis in our anisotropic expanding universe. This paper proceeds a modified redshift in anisotropic cosmological model as 1 + (z) over tilde (t, (p) over cap) = a(t(0))/a(t) (1 - A((n) over cap.(p) over cap)) (where A is the magnitude of anisotropy, (n) over cap is the direction of privileged axis, and (p) over cap is the direction of each SNe Ia sample to galactic coordinates) along with anisotropic parameter delta = A((n) over cap.(p) over cap)/1+A((n) over cap.(p) over cap). The luminosity distance is expanded with model-independent cosmographic parameters as a function of modified redshift (z) over tilde. As the transformation matrix M(nxn) is obtained to convert the Taylor series coefficients of isotropic luminosity distance to corresponding anisotropic parameters. These results culminate the magnitude of anisotropy about vertical bar A vertical bar similar or equal to 10(-3) and the direction of preferred axis as (l, b) = (297(-34)(+34), 3(-28)(+28)), which are consistent with other studies in 1-sigma confidence level.