Combining spectroscopic and photometric surveys using angular cross-correlations I: Algorithm and modelling

Understand

Weak lensing (WL) clustering is studied using 2D (angular) coordinates, while redshift space distortions (RSD) and baryon acoustic oscillations (BAO) use 3D coordinates, which requires a model dependent conversion of angles and redshifts into comoving distances.

• This is the first paper of a series, which explore modelling multi-tracer galaxy clustering (of WL, BAO and RSD), using only angular (2D) cross-correlations in thin redshift bins.
• This involves evaluating many thousands cross-correlations, each a multidimensional integral, which is computationally demanding.
• We present a new algorithm that performs these calculations as matrix operations.