Implications of bias evolution on measurements of the integrated Sachs-Wolfe effect: errors and biases in parameter estimation

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The subject of this paper is a quantification of the impact of uncertainties in bias and bias evolution on the interpretation of measurements of the integrated Sachs-Wolfe effect, in particular on the estimation of cosmological parameters. We carry out a Fisher-matrix analysis for quantifying the degeneracies between the parameters of a dark energy cosmology and bias evolution, for the combination of the PLANCK microwave sky survey with the EUCLID main galaxy sample, where bias evolution b(a)=b₀+(1-a)bₐ is modelled with two parameters b₀ and bₐ. Using a realistic bias model introduces a characteristic suppression of the iSW-spectrum on large angular scales, due to the altered distance-weighting functions. The errors in estimating cosmological parameters if the data with evolving bias is interpreted in the framework of cosmologies with constant bias is quantified in an extended Fisher-formalism. We find that the best-fit values of all parameters are shifted by an amount comparable to the statistical accuracy: The estimation bias in units of the statistical accuracy amounts to 1.19 for Omegaₘ, 0.27 for sigma₈, and 0.72 for w for bias evolution with bₐ=1. Leaving bₐ open as a free parameter deteriorates the statistical accuracy, in particular on Omegaₘ and w.