Redshift Distortions as a Probe of Gravity

Understand

Redshift distortion measurements from galaxy surveys include sensitivity to the gravitational growth index distinguishing other theories from Einstein gravity.

• This gravitational sensitivity is substantially free from uncertainty in the effective equation of state of the cosmic expansion history.
• We also illustrate the bias in the traditional application to matter density determination using f=Omega_m(a)^{0.6}, and how to avoid it.