Detection significance of Baryon Acoustic Oscillations peaks in galaxy
  and quasar clustering
  We compare our analysis of the Baryon Acoustic Oscillations (BAO) feature in
the correlation functions of SDSS BOSS DR12 LOWZ and CMASS galaxy samples with
the findings of arXiv:1509.06371v2. Using subsets of the data we obtain an
empirical estimate of the errors on the correlation functions which are in
agreement with the simulated errors of arXiv:1509.06371v2. We find that the
significance of BAO detection is the quantity most sensitive to the choice of
the fitting range with the CMASS value decreasing from $8.0\sigma$ to
$5.3\sigma$ as the fitting range is reduced. Although our measurements of
$D_V(z)$ are in agreement with those of arXiv:1509.06371v2, we note that their
CMASS $8.0\sigma$ (LOWZ $4.0\sigma$) detection significance reduces to
$4.7\sigma$ ($2.8\sigma$) in fits with their diagonal covariance terms only. We
extend our BAO analysis to higher redshifts by fitting to the weighted mean of
2QDESp, SDSS DR5 UNIFORM, 2QZ and 2SLAQ quasar correlation functions, obtaining
a $7.6\%$ measurement compared to $3.9\%$ achieved by eBOSS DR14. Unlike for
the LRG surveys, the larger error on quasar correlation functions implies a
smaller role for nuisance parameters (accounting for scale-dependent
clustering) in providing a good fit to the fiducial $\Lambda$CDM model. Again
using only the error bars of arXiv:1705.06373v2 and ignoring any off-diagonal
covariance matrix terms, we find that the eBOSS peak significance reduces from
2.8 to $1.4\sigma$. We conclude that for both LRGs and quasars, the reported
BAO peak significances from the SDSS surveys depend sensitively on the accuracy
of the covariance matrix at large separations.
