Self-calibration and robust propagation of photometric redshift distribution uncertainties in weak gravitational lensing

Understand

We present a method that accurately propagates residual uncertainties in photometric redshift distributions into the cosmological inference from weak lensing measurements.

• The redshift distributions of tomographic redshift bins are parameterised using a flexible modified Gaussian mixture model.
• We fit this model to pre-calibrated redshift distributions and implement an analytic marginalisation over the potentially several hundred redshift nuisance parameters in the weak lensing likelihood, which is demonstrated to accurately recover the cosmological posterior.
• By iteratively fitting cosmological and nuisance parameters arising from the redshift distribution model, we perform a self-calibration of the redshift distributions via the tomographic cosmic shear measurements.