Simultaneous constraints on bias, normalization and growth index through power spectrum measurements

In this Letter, we point out that redshift surveys can break the degeneracy between the galaxy bias, the power spectrum normalization, s8, 0, and the growth factor, without the need for external information by using a simple and rather general parametrization for the growth rate, the well-known ? parametrization and measuring the power spectrum at least at two different redshifts. We find that in next-generation surveys like Euclid, s8, 0 and ? can be measured to within 1 and 5 per cent, respectively, while the bias b(z) can be measured to within 12 per cent in each of 14 equal-width redshift bins spanning 0.7 =z= 2.