Consistency check of {\Lambda}CDM phenomenology

TL;DR

This paper tests the consistency of the LCDM cosmological model by relaxing key assumptions and analyzing multiple observational data sets, finding it remains consistent within 95% confidence despite extended parameterizations.

Contribution

It introduces a comprehensive framework allowing deviations from LCDM assumptions and assesses their compatibility with diverse cosmological observations.

Findings

LCDM remains consistent at 95% confidence level under extended models.

Relaxing assumptions does not significantly improve fit, supporting LCDM's robustness.

Separate constraints on background and growth parameters may exclude viable models.

Abstract

The standard model of cosmology LCDM assumes general relativity, flat space, and the presence of a positive cosmological constant. We relax these assumptions allowing spatial curvature, time-dependent effective dark energy equation of state, as well as modifications of the Poisson equation for the lensing potential, and modifications of the growth of linear matter density perturbations in alternate combinations. Using six parameters characterizing these relations, we check LCDM for consistency utilizing cosmic microwave background anisotropies, cross correlations thereof with high-redshift galaxies through the integrated Sachs-Wolfe effect, the Hubble constant, supernovae and baryon acoustic oscillation distances, as well as the relation between weak gravitational lensing and galaxy flows. In all scenarios, we find consistency of the concordance model at the 95% confidence level. However, we emphasize that constraining supplementary background parameters and parametrizations of the growth of large-scale structure separately may lead to a priori exclusion of viable departures from the concordance model.