Searching for a Cosmological Preferred Axis in complicated class of cosmological models:Case study $f(R,T)$ model

Abstract

Recent astronomical observations show that the universe may be anisotropic on large scales. The Union2 SnIa data hint that the universe has a preferred direction. If such a cosmological privileged axis indeed exists, one has to consider an anisotropic expanding Universe instead of the isotropic cosmological model. In this paper, we present a detailed analysis of the dark energy dipole in $f(R,T)=f_{1}(R)+f_{2}(T)$ Cosmological Model using three types of dipole fit (DF) method which are (I)dipole + monopole fitting for distance modulus(DMFDM), (II)dipole + monopole fitting for luminosity distance(DMFLD) and (III) general dipole fitting for luminosity distance(GDFLD). We have found the maximum anisotropic deviation direction for (DMFDM) method as $(l, b)=(315^{+25}_{-25},-23^{+14}_{-15})$, for (DMFLD) as $(l, b)=(l, b)=(315^{+35}_{-37},-23^{+18}_{-18})$, and for (GDFLD) method as $(l, b)=(317^{+32}_{-32},-23^{+18}_{-18})$ which are located very close to each other. We compare our model with the $CPL$, $ΛCDM$ and $ωCDM$ models. Constraints on $(l, b)$ in $f(R, T)$ model are not much different from the cases of the $CPL$, $ΛCDM$ and $ωCDM$ models. Moreover, the results are consistent with other studies.