Constraints on Galaxy Bias, Matter Density, and Primordial Non-Gaussianity from thePSCzGalaxy Redshift Survey

We compute the bispectrum for the IRAS PSCz catalog and find that the galaxy distribution displays the characteristic signature of gravity. Assuming Gaussian initial conditions, we obtain galaxy biasing parameters 1/b₁0ex0ex=0ex0ex1.20_-0.19+0.18 and b₂/b₁²0ex0ex=0ex0ex-0.42±0.19, with no sign of scale-dependent bias for k≤0.3hMpc^-1. These results impose stringent constraints on non-Gaussian initial conditions. For dimensional scaling models with χN² statistics, we find $N>49$, which implies a constraint on primordial skewness B₃<0.35.