LONG-DISTANCE CORRELATIONS IN THE GALAXY DISTRIBUTION AND THE NATURE OF DARK-MATTER

Specific anomalies in the spatial correlation function xi(r) and the p rojected angular correlation function w(theta) of galaxy distributions in cosmological models with baryonic dark matter and isocurvature ini tial perturbations are discussed. These anomalies are found at r almos t-equal-to R and r almost-equal-to 2R in xi(r), where R is the acousti c horizon at the moment of the last scattering of relict radiation. An alogous anomalies occur in w(theta) at the corresponding angles theta( R) and 2theta(R). We call these anomalies long distance correlations ( LDCs). They are consequences of the secondary sound waves that arise i n the ionized plasma from the initial isocurvature perturbations. We i nvestigate the dependence of the properties of the LDCs on the paramet ers of the models, and emphasize that these properties are very sensit ive to the nature of dark matter. The possibility of observing the LDC effect is discussed. We propose a special method for the filtering of this effect in observational data.