Barry and the BAO Model Comparison
  We compare the performance of four state-of-the-art models for extracting
isotropic measurements of the Baryon Acoustic Oscillation (BAO) scale. To do
this, we created a new, public, modular code Barry, which contains datasets,
model fitting tools, and model implementations incorporating different
descriptions of non-linear physics and algorithms for isolating the BAO
feature. These are then evaluated for bias, correlation, and fitting strength
using mock power spectra and correlation functions developed for the Sloan
Digital Sky Survey Data Release 12. Our main findings are as follows: 1) All of
the models can recover unbiased constraints when fit to the pre- and
post-reconstruction simulations. 2) Models that provide physical descriptions
of the damping of the BAO feature (using e.g., standard perturbation or
effective-field theory arguments) report smaller errors on average, although
the distribution of mock $\chi^{2}$ values indicates these are underestimated.
3) Allowing the BAO damping scale to vary can provide tighter constraints for
some mocks, but is an artificial improvement that only arises when noise
randomly sharpens the BAO peak. 4) Unlike recent claims in the literature when
utilising a BAO Extractor technique, we find no improvement in the accuracy of
the recovered BAO scale. 5) We implement a procedure for combining all models
into a single consensus result that improves over the standard method without
obviously underestimating the uncertainties. Overall, Barry provides an
excellent framework for performing the cosmological analyses for upcoming
surveys, and for rapidly testing and validating new models.
