Observational constraints on the LLTB model

TL;DR

This paper compares the standard LCDM cosmological model with inhomogeneous LTB void models, analyzing observational data to assess their viability and exploring the parameter space where each model fits the data.

Contribution

It provides a comprehensive likelihood analysis of LTB models with cosmological constant, showing their viability under certain conditions and their differences from LCDM.

Findings

LCDM is not the only compatible model with observations.

Matter-only void models can fit data if BAO constraints are relaxed.

Small local voids do not significantly impact LCDM parameter estimation.

Abstract

We directly compare the concordance LCDM model to the inhomogeneous matter-only alternative represented by LTB void models. To achieve a "democratic" confrontation we explore LLTB models with non-vanishing cosmological constant and perform a global likelihood analysis in the parameter space of cosmological constant and void radius. In our analysis we carefully consider SNe, Hubble constant, CMB and BAO measurements, marginalizing over spectral index, age of the universe and background curvature. We find that the LCDM model is not the only possibility compatible with the observations, and that a matter-only void model is a viable alternative to the concordance model only if the BAO constraints are relaxed. Moreover, we will show that the areas of the parameter space which give a good fit to the observations are always disconnected with the result that a small local void does not significantly affect the parameter extraction for LCDM models.