Probing primordial non-Gaussianity with large-scale structure

We consider primordial non-Gaussianity due to quadratic corrections in the gravitational potential parametrized by a nonlinear coupling parameter f(NL). We study constraints on f(NL) from measurements of the galaxy bispectrum in redshift surveys. Using estimates for idealized survey geometries of the 2dF and SDSS surveys and realistic ones from SDSS mock catalogs, we show that it is possible to probe f(NL)similar or equal to100, after marginalization over bias parameters. We apply our methods to the galaxy bispectrum measured from the PSCz survey, and obtain a 2sigma constraint f(NL)less than or similar to1800. We estimate that an all sky redshift survey up to zsimilar or equal to1 can probe f(NL)similar or equal to1. We also consider the use of cluster abundance to constrain f(NL) and find that in order to be sensitive to f(NL)similar or equal to100, cluster masses need to be determined with an accuracy of a few percent, assuming perfect knowledge of the mass function and cosmological parameters.