Day 1258

Wednesday.

1705.05442
Optimized clustering estimators for BAO measurements accounting for significant redshift uncertainty
Ross, et al

Determine an optimized clustering statistic to be used for galaxy samples with significant redshift uncertainty, such as those that rely on photometric redshifts.  To do so, study the BAO information content as a function of the orientation of galaxy clustering modes with respect to their angle to the LOS.  The clustering along the LOS, as observed in a redshift-space with significant redshift uncertainty, has contributions from clustering modes with a range of orientations with respect to the true LOS.  For z uncertainty sigma_z>=0.02(1+z), find that while the BAO information is confined to transverse clustering modes in the true space, it is spread nearly evenly in the observed space.  Thus, measuring clustering in terms of the projected separation (regardless of the LOS) is an efficient and nearly lossless compression of the signal for sigma_z>=0.02(1+z).  For reduced z uncertainty, a more careful consideration is required.  Use more than 1700 realizations of galaxy simulations mimicking the DES Year1 sample to validate the analytic results and optimized analysis procedure.  Find that using the correlation function binned in projected separation, can achieve uncertainties that are within 10% of those predicted by Fisher matrix forecasts.  Predict that DES Y1 should achieve a 5% distance measurement using the optimized methods.  Expect the results presented here to be important for any future BAO measurements made using photo-z data.