Looking Beyond Lambda with the Union Supernova Compilation

TL;DR

This paper evaluates various cosmological models against supernova, CMB, and BAO data, identifying which models align with observations and highlighting the potential of future data to constrain dark energy physics.

Contribution

It provides a comprehensive analysis of scalar field, modified gravity, and phenomenological models using the latest supernova compilation, extending beyond Lambda to test their viability.

Findings

Some models are inconsistent with data

Certain models are statistically favored over LCDM

Two-parameter dark energy models have significant viable parameter space

Abstract

The recent robust and homogeneous analysis of the world's supernova distance-redshift data, together with cosmic microwave background and baryon acoustic oscillation data, provides a powerful tool for constraining cosmological models. Here we examine particular classes of scalar field, modified gravity, and phenomenological models to assess whether they are consistent with observations even when their behavior deviates from the cosmological constant Lambda. Some models have tension with the data, while others survive only by approaching the cosmological constant, and a couple are statistically favored over LCDM. Dark energy described by two equation of state parameters has considerable phase space to avoid Lambda and next generation data will be required to constrain such physics.