Analysing Ultra High Energy Cosmic Rays' Anisotropy in $\boldsymbol{f(R, T)}$ Gravity Theory

TL;DR

This paper compares the anisotropy of ultra-high energy cosmic rays across different cosmological models, highlighting how $f(R,T)$ gravity predicts more isotropic cosmic ray distributions than the standard $Lambda$CDM model.

Contribution

It introduces the analysis of UHECR anisotropy within $f(R,T)$ gravity models, providing a comparative study against the standard $Lambda$CDM cosmology.

Findings

$f(R,T)$ models show lower anisotropy amplitude, indicating more isotropic cosmic ray distribution.

$Lambda$CDM predicts higher anisotropy amplitude at most energies.

The anisotropy amplitude is highly sensitive to the underlying cosmological model.

Abstract

In this study, we investigated the anisotropy of diffusive Ultra-High Energy Cosmic Rays (UHECRs) by employing three cosmological models: two models from the $f(R, T)$ gravity theory and the other is the standard $\Lambda$CDM model. The primary objective of this work was to ascertain the role of the $f(R, T)$ gravity theory in comprehending the anisotropy of UHECRs without implicitly endorsing the conventional cosmology. We parameterized the magnetic field and the source distance in anisotropy calculations to align well with the observational data from the Pierre Auger Observatory for all the cosmological models. An uncertainty band is presented along with the $\chi^2$ test for all cosmological models to demonstrate the goodness of fitting. Our findings revealed that the amplitude of the anisotropy is highly sensitive to these cosmological models. Notably, the $f(R, T)$ models exhibited a lower amplitude of anisotropy (i.e., more isotropy), while the $\Lambda$CDM model predicted a comparatively higher amplitude at most of the energies considered.