The LSST-DESC 3x2pt Tomography Optimization Challenge

This paper presents the results of Rubin Observatory Dark Energy Science Collaboration (DESC) 3x2pt tomography challenge, which served as a first step toward optimizing tomographic binning strategy for main DESC analysis. The task choosing an optimal scheme photometric survey is made particularly delicate in context metacalibrated lensing catalogue, only photometry from bands included metacalibration process (usually riz and potentially g) can be used sample definition. goal challenge was to collect compare bin assignment strategies under various metrics standard cosmology analysis highly idealized setting establish baseline realistically complex follow-up studies; this preliminary study, we two sets cosmological simulations galaxy redshifts simple noise model neglecting outliers variation observing conditions, contributed algorithms were provided with representative complete training set. We review evaluate entries finding that even limited information, multiple separate bins reasonably well, reaching figures-of-merit scores close attainable maximum. further find adding g band improves metric performance by ~15% depends strongly on science case: figure-of-merit optimized, observables (clustering, lensing, or both) are included.