Large-Scale Clustering from Non-Gaussian Texture Models

A basic ingredient to understand large scale fluctuations in our present dayUniverse is the initial conditions. Using N-body simulations, we compare theclustering that arises from Gaussian and non-Gaussian initial conditions. Thelatter is motivated by a global texture model which has initial $J$-ordercorrelations $\xibar_J$ close to the strongly non-Gaussian regime $\xibar_J\simeq \xibar_2^{J/2}$. The final amplitudes $S_J \equiv\xibar_J/\xibar_2^{J-1}$ in the non-Gaussian (texture) model evolves slowlytowards the (Gaussian) gravitational predictions but, even at $\sigma_8=1$, arestill significantly larger, showing a characteristic minimum with a sharpincrease in $S_J$ with increasing scales. This minimum, which is between $10$and $15 \Mpc$, depending on the normalization, separates the regime wheregravity starts dominating the evolution from the one in which the initialconditions are the dominant effect. In comparing this results with galaxyclustering observations, one has to take into account {\it biasing}, i.e. howgalaxy fluctuations trace matter fluctuations. Although biasing could changethe amplitudes, we show that the possible distortions to the shape of $S_J$ aretypically small. In contrast to the non-Gaussian (texture) predictions, we findno significant minimum or rise in $S_J$ obtained from the APM Galaxy Survey.Comment: revised version to appear in ApJ Let., gzip postscrip