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

TL;DR

This study investigates the possible existence of a preferred cosmological axis using $f(R,T)$ models and various dipole fitting methods, finding consistent anisotropic directions aligned with previous observations.

Contribution

It introduces a detailed analysis of dark energy dipole in $f(R,T)$ models using three dipole fit methods, revealing a preferred axis close to prior findings.

Findings

Identified a preferred axis near (l, b)=(315°, -23°) across methods.

Constraints on the axis are similar to those in $ ext{CPL}$, $ ext{Lambda CDM}$, and $ ext{omega CDM}$ models.

Results align with previous studies on cosmological anisotropy.

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 $CPL$, $\Lambda CDM$ and $\omega CDM$ models. Constraints on $(l, b)$ in $f(R, T)$ model are not much different from the cases of the $CPL$, $\Lambda CDM$ and $\omega CDM$ models. Moreover, the results are consistent with other studies.