Non-Gaussian halo bias and future galaxy surveys

We forecast constraints on primordial non-Gaussianity achievable from forthcoming surveys by exploiting the scale-dependent halo bias introduced on large scales by non-Gaussian initial conditions. We explore the performance of exploiting both the shape of the galaxy power spectrum on large scales and the cross-correlation of galaxies with cosmic microwave background maps through the integrated Sachs-Wolfe effect. We find that future surveys can detect primordial non-Gaussianity of the local form with a non-Gaussianity parameter of order |f(NL)| unity. This is particularly exciting because, while the simplest single- field slow- roll models of inflation predict a primordial, |f(NL)| << 1, this signal sources extra contributions to the effective f(NL) of large-scale structures that are expected to be above our predicted detection threshold.