# Intrinsically symmetric cosmological model in the presence of dissipative fluids

## TL;DR

This paper presents an exact inhomogeneous cosmological solution with dissipative fluids, showing it can mimic standard cosmological models without exotic matter, highlighting the importance of exploring various inhomogeneous models for observational consistency.

## Contribution

It introduces a new exact inhomogeneous cosmological model with dissipative fluids based on intrinsic symmetries, expanding the set of solutions compatible with observations.

## Key findings

- Inhomogeneities can produce effective deceleration parameters similar to standard models.
- The model fits observational data without requiring exotic matter.
- Different boundary conditions lead to models compatible with ΛCDM or LTB.

## Abstract

Based upon the intrinsic symmetries approach to inhomogeneous cosmologies, we propose an exact solution to Einstein's field equations where the spatial sections are flat and the source is a non-perfect fluid such that the dissipative terms can be written in terms of spatial gradients of the energy density under a suitable choice of the coordinate system. It is shown through the calculation of the luminosity distance as a function of the redshift that the presence of such inhomogeneities may lead to an effective deceleration parameter compatible with either the standard $\Lambda$CDM model or LTB models depending on the choice of boundary conditions with no exotic matter. This fact is another evidence that different inhomogeneous models should be carefully investigated in order to verify which model may be compatible with observations and still be as close as possible to the standard model regarding the underlying assumptions, without resorting necessarily to exotic matter components.