Orateur
Description
Upcoming photometric surveys such as Euclid and LSST will combine galaxy clustering and weak lensing to constrain dark energy, but exploiting mildly non-linear scales requires additional nuisance parameters for galaxy bias and intrinsic alignments, which degrade cosmological constraints. We present a framework combining 1-loop power spectra (3×2pt) with tree-level auto- and cross-bispectra of galaxy clustering and weak lensing (4×3pt), including intrinsic alignments in the TATT model. Second-order nuisance parameters enter power spectra only through loop corrections, but contribute to bispectra already at tree level, so that bispectra can calibrate them efficiently. Performing a Fisher forecast for a Stage IV survey, we show that adding the 4×3pt to the 3×2pt improves dark energy constraints, mostly through this calibration. Since the full 4×3pt becomes computationally prohibitive for a large number of tomographic bins, we also show that a small set of skew-spectra recovers most of its information.