Fitting the Union2.1 SN Sample with the R_h=ct Universe

TL;DR

This paper compares the R_h=ct universe model with the standard LCDM model using Type Ia supernova data, finding that both produce similar distance profiles, but the fit can be improved with model-specific data optimization.

Contribution

It demonstrates that the R_h=ct model fits supernova data comparably to LCDM and highlights the importance of model-dependent data reduction in cosmological analyses.

Findings

R_h=ct and LCDM produce similar supernova distance profiles.

Current supernova data reduction is model-dependent, affecting comparative analyses.

Optimizing data with R_h=ct improves fit quality.

Abstract

The analysis of Type Ia supernova data over the past decade has been a notable success story in cosmology. These standard candles offer us an unparalleled opportunity of studying the cosmological expansion out to a redshift of ~1.5. The consensus today appears to be that LCDM offers the best explanation for the luminosity-distance relationship seen in these events. However, a significant incompatibility is now emerging between the standard model and other equally important observations, such as those of the cosmic microwave background. LCDM does not provide an accurate representation of the cosmological expansion at high redshifts (z>>2). It is therefore essential to re-analyze the Type Ia supernova data in light of the cosmology (the R_h=ct Universe) that best represents the Universe's dynamical evolution at early times. In this paper, we directly compare the distance-relationship in LCDM with that predicted by R_h=ct, and each with the Union2.1 sample, and show that the two theories produce virtually indistinguishable profiles, though the fit with R_h=ct has not yet been optimized. This is because the data cannot be determined independently of the assumed cosmology---the supernova luminosities must be evaluated by optimizing 4 parameters simultaneously with those in the adopted model. This renders the data compliant to the underlying theory, so the m odel-dependent data reduction should not be ignored in any comparative analysis between competing cosmologies. In this paper, we use R_h=ct to fit the data reduced with LCDM, and though quite promising, the match is not perfect. An even better fit would result with an optimization of the data using R_h=ct from the beginning.