Linear point standard ruler for galaxy survey data: Validation with mock catalogs

Due to late-time nonlinearities, the location of the acoustic peak in the two-point galaxy correlation function is a redshift-dependent quantity, and thus it cannot he simply employed as a cosmological standard ruler. This has motivated the recent proposal of a novel ruler, also located in the baryon acoustic oscillation range of scales of the correlation function, dubbed the linear point. Unlike the peak, it is insensitive at the 0.5% level to many of the nonlinear effects that distort the clustering correlation function and shift the peak. However, this is not enough to make the linear point a useful standard ruler. In addition, we require a model-independent method to estimate its value from real data, avoiding the need to deploy a poorly known nonlinear model of the correlation function. In this manuscript, we precisely validate a procedure for model-independent estimation of the linear point. We also identify the optimal setup to estimate the linear point from the correlation function using galaxy catalogs. The methodology developed here is of general validity and can be applied to any galaxy correlation-function data. As a working example, we apply this procedure to the LOWZ and CMASS galaxy samples of the Twelfth Data Release of the Baryon Oscillation Spectroscopic Survey, for which the estimates of cosmic distances using the linear point have been presented by Anselmi et al.