1206.6289 (Fulvio Melia)

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

Fulvio Melia

The analysis of Type Ia supernova data over the past decade has provided one of the most notable success stories in cosmology. Arguably the most reliable standard candles we have to date, they 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. These studies indicate that LCDM does not provide an accurate representation of the cosmological expansion at high redshifts (z >> 2). It has therefore become 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 the R_h=ct Universe, and each with the Union2.1 sample, and show that the two theories produce virtually indistinguishable profiles. In so doing, we directly address recent criticisms of the R_h=ct cosmology based on analysis of the Type Ia supernova observations. We suggest that fitting the data with LCDM compels it to relax to the R_h=ct Universe, which has no free parameters. However, we also highlight the fact that the data cannot be determined independently of the assumed cosmology, because 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, suggesting that one should not ignore the model-dependent data reduction in any comparative analysis between competing cosmologies.

View original: http://arxiv.org/abs/1206.6289