A Comparison of Cosmological Models Using Time Delay Lenses
2014-06-14In this work, we broaden the base of supportfor this new, important cosmic probe by using these observations to carry out a one-on-one comparison betweenΛCDM and theR_h= ct universe. To facilitate a direct comparison between these two competing models,we showin Figure 1 the 12 observed time-delay distance R_obs comparedwith those predicted by these two theoretical models.
( By with WEI Jun-Jie )
Figure 1. 2D region with the 1σ and 2σ contours for the parameters H0 and η in the Rh = ct universe, using a sample of 1000 time-delay lenses, simulated
with Rh = ct as the background cosmology. The assumed value for H
The currently available sample indicates a likelihood of ~70%–80% that the R_h= ctuniverseis the correct cosmology versus ~20%–30% for the standard model. Thispossibly interesting result reinforces theneed to greatly expand the sample of time-delay lenses, e.g., with the successful implementation of the Dark EnergySurvey, the VST ATLAS survey, and the Large Synoptic Survey Telescope. In anticipation of a greatly expandedcatalog of time-delay lenses identified with these surveys, we have produced synthetic samples to estimate howlarge they would have to be in order to rule out either model at a ~99.7% confidence level. We find that if the realcosmology is ΛCDM, a sample of ~150 time-delay lenses would be sufficient to rule out R_h= ctat this levelof accuracy, while ~1000 time-delay lenses would be required to rule out ΛCDM if the real universe is insteadR_h= ct. This difference in required sample size reflects the greater number of free parameters available to fit thedata with ΛCDM.