Speaker: Chaz Shapiro
Location: Dark Cosmology Centre, Copenhagen
Assuming General Relativity is correct on large-scales, Redshift-Space Distortions (RSDs) and the Integrated Sachs-Wolfe effect (ISW) are both sensitive to the time derivative of the linear growth function. We investigate the extent to which these probes provide complementary or redundant information when they are combined to constrain the amplitude of the linear velocity power spectrum, often quantified by the function f?8(z). Using a 3D spherical harmonic expansion, we compute the covariance matrices of the signals for a redshift survey like BOSS combined with a CMB survey like Planck. The spherical harmonic basis allows accurate ISW estimates by avoiding the plane-parallel approximation, and it retains RSD information that is otherwise lost when projecting angular clustering onto redshift shells. We find that the correlation between the ISW and RSD signals are low as the probes are sensitive to different modes. On large scales (k < 0.05 Mpc/h), the ISW can improve constraints on f?8 by more than 10% compared to using RSDs alone. When RSD measurements are available on smaller scales, the ISW does not significantly improve constraints on a scale-independent f?8 under General Relativity.