THE DISTRIBUTION OF IRAS GALAXIES ON LINEAR AND NONLINEAR SCALES

We analyze the galaxy distribution functions for voids and counts-in-cells using the IRAS catalog. Angular diameter scales, the largest probed to date, range from 0.5-degrees to 30-degrees, corresponding to linear diameters less than or similar to 40 h-1 Mpc. The analysis develops a new technique which has no free parameters. On all scales, the results agree closely with predictions of simple gravitational galaxy clustering. The value of b(pattern) for the IRAS galaxies at a cell diameter of 30-degrees is 0.62 +/- 0.03. It is nearly independent of scale for angular diameters greater than or similar to 20-degrees. We also develop a new method for using the projected distribution functions to estimate the average amplitude, -epsilon, and scale, r(neg), where the spatial two-point galaxy correlation function, xi2, becomes negative. This technique is sensitive to the negative range of xi2 and is independent of the peculiar velocity effects which make measurements of the spatial correlation function uncertain on some scales. It shows that a large class of CDM-related models, with linear biasing, appears to be inconsistent with the IRAS distribution. We discuss some implications for the selection of the IRAS galaxies, the scale invariance of higher order moments of the IRAS distribution function, and the evidence that initial conditions for galaxy clustering were Gaussian.