Large-Scale Angular Correlations in Cold Dark Matter Models

We investigate the behavior of the angular galaxy function, w(theta), in the framework of cold dark matter (CDM) models. We compare the situation for the standard CDM model with Gaussian initial fluctuations with comparable CDM models with nonrandom phases. We have generated artificial Lick maps using the results of N-body simulations. We compare the w(theta) measured from the simulations with the APM correlation (scaled to the depth of the Lick map). For the Gaussian CDM model, we find that neither the standard normalization (b = 1.5) nor a more evolved model (b = 1, as suggested by the COBE data), can reproduce the correlations on large angular scales (theta of about 2.5 deg or greater). We come to a similar conclusion about CDM models with positively skewed initial fluctuation distributions. In contrast, models with initially negatively skewed fluctuations produce a w(theta) that declines much more gently on large scales. Such models are therefore, at least in principle, capable of reconciling the lack of large-scale power of the CDM spectrum with the observed clustering of APM galaxies