The scatter, residual correlations and curvature of the SPARC baryonic
  Tully-Fisher relation
  In recent work, Lelli et al. (2016) argue that the tightness of the baryonic
Tully-Fisher relation (BTFR) of the SPARC galaxy sample, and the weakness of
the correlation of its residuals with effective radius, pose challenges to LCDM
cosmology. In this Letter we calculate the statistical significance of these
results in the framework of halo abundance matching, which imposes a canonical
galaxy-halo connection. Taking full account of sample variance among SPARC-like
realisations of the parent halo population, we find the scatter in the
predicted BTFR to be 3.6 sigma too high, but the correlation of its residuals
with galaxy size to be naturally weak. Further, we find abundance matching to
generate BTFR curvature in 3.0 sigma disagreement with the data, and a fraction
of galaxies with non-flat rotation curves somewhat larger than observed.
