Spectroscopic failures in photometric redshift calibration: Cosmological biases and survey requirements

Abstract

We use N-body-spectrophotometric simulations to investigate the impact of incompleteness and incorrect redshifts in spectroscopic surveys on photometric redshift training and calibration and the resulting effects on cosmological parameter estimation from weak lensing shear-shear correlations. The photometry of the simulations is modelled after the upcoming Dark Energy Survey and the spectroscopy is based on a low/intermediate-resolution spectrograph with wavelength coverage of 5500 1.3. We discuss several approaches for reducing the cosmological biases, in particular finding that photo-z error estimators can reduce biases appreciably when the photo-z errors are correlated with the spectroscopic failures, but not otherwise.