Real-space cosmic fields from redshift-space distributions: a Green   function approach
  We present a new method for reconstructing the cosmological density, peculiar velocity and peculiar gravitational potential on large scales from redshift data. We remove the distorting effects of line-of-sight peculiar motions by using the linear theory of gravitational instability, in which the potential is the solution to a linear partial differential equation first derived by Kaiser. We solve this equation by deriving its Green function; the Green functions for the peculiar velocity and the real-space density follow directly. Reconstruction of the cosmic fields is thus reduced to integration over redshift space with the appropriate Green function kernel. Our algorithm has a single input parameter, beta=Omega^0.6/b, where b is the linear bias factor and Omega is the cosmological density parameter. We discuss the virtues of this method for error control, for estimating beta, and for constraining the bias mechanism. 
Max Tegmark, Benjamin Bromley