Exploring Alternative Cosmologies with the LSST: Simulated Forecasts and Current Observational Constraints

TL;DR

This paper evaluates the potential of LSST and other datasets to constrain alternative dark energy models, finding that LSST data could significantly improve parameter constraints and reveal deviations from the standard LCDM model.

Contribution

It provides simulated forecasts demonstrating LSST's capacity to tighten constraints on dynamic dark energy models and highlights the importance of future LSST observations in cosmology.

Findings

LSST data offers tighter dark energy parameter constraints.

Inclusion of BAO improves model constraints.

Deviations from LCDM exceed 2-sigma in most datasets.

Abstract

In recent years, the Lambda Cold Dark Matter (LCDM) model, which has been pivotal in cosmological studies, has faced significant challenges due to emerging observational and theoretical inconsistencies. This paper explores alternative cosmological models to address these discrepancies, using simulated three years photometric Supernovae Ia data from the Legacy Survey of Space and Time (LSST), supplemented with additional Pantheon+, Union, and the recently released Dark Energy Survey 5 Years (DESY5) supernova compilations and Baryon Acoustic Oscillation (BAO) measurements. We assess the constraining power of these datasets on various dynamic dark energy models, including CPL, BA, JBP, SCPL, and GCG. Our analysis demonstrates that the LSST with its high precision data, can provide tighter constraints on dark energy parameters compared to other datasets. Additionally, the inclusion of BAO measurements significantly improves parameter constraints across all models. Except for Pantheon+, we find that across all the cosmological datasets, and the dark energy models considered in this work, there is a consistent deviation from the LCDM model that exceeds a 2-sigma significance level. Our findings underscore the necessity of exploring dynamic dark energy models, which offer more consistent frameworks with fundamental physics and observational data, potentially resolving tensions within the LCDM paradigm. Furthermore, the use of simulated LSST data highlights the survey's potential in offering significant advantages for exploring alternative cosmologies, suggesting that future LSST observations would play a crucial role.