Dipole Cosmology in $f(Q)$-gravity

TL;DR

This paper explores symmetric teleparallel $f(Q)$-gravity with a tilted perfect fluid in Kantowski-Sachs spacetime, revealing that its dynamics reduce to vacuum solutions of STEGR, including Kasner and de Sitter universes.

Contribution

It introduces a dipole cosmological model in $f(Q)$-gravity with a tilted perfect fluid and analyzes its evolution, showing reduction to known vacuum solutions.

Findings

Dynamics reduce to vacuum solutions of STEGR.

Includes Kasner and de Sitter universes as special cases.

Extreme tilt leads to anisotropic and accelerated universe.

Abstract

Symmetric teleparallel $f(Q)$-gravity allows for the presence of a perfect fluid with a tilted velocity in the Kantowski-Sachs geometry. In this dipole model, we consider an ideal gas and we investigate the evolution of the physical parameters. The tilt parameter is constrained by the nonlinear function $f(Q)$ through the non-diagonal equations of the field equations. We find that the dynamics always reduce to the vacuum solutions of STEGR. This includes the Kasner universe, when no cosmological term is introduced by the $f(Q)$ function, and the isotropic de Sitter universe, where $f\left( Q\right) $ plays the role of the cosmological constant. In the extreme tilt limit, the universe is consistently anisotropic and accelerated. However, the final solution matches that of STEGR.