A TEST OF THE ADHESION APPROXIMATION FOR GRAVITATIONAL CLUSTERING

We quantitatively compare a particle implementation of the adhesion ap proximation to fully nonlinear, numerical ''N-body'' simulations. Our primary tool, cross-correlation of N-body simulations with the adhesio n approximation, indicates good agreement, better than that found by t he same test performed with the Zel'dovich approximation (hereafter ZA ). However, the cross-correlation is not as good as that of the trunca ted Zel'dovich approximation (TZA), obtained by applying the Zel'dovic h approximation after smoothing the initial density field with a Gauss ian filter. We confirm that the adhesion approximation produces an exc essively filamentary distribution. Relative to the N-body results, we also find that: (a) the power spectrum obtained from the adhesion appr oximation is more accurate that that from ZA or TZA, (b) the error in the phase angle of Fourier components is worse that that from TZA, and (c) the mass distribution function is more accurate than that from ZA or TZA. It appears that adhesion performs well statistically, but tha t TZA is more accurate dynamically, in the sense of moving mass to the right place.