Clustering bias in the nearby galaxies catalog and in cold dark matter models

The cold dark matter theory predicts that the clustering of galaxies should be an increasing function of the circular velocity of the dark halos in which they were formed. We show that an effect of this kind is present in the Nearby Galaxies Catalog at about the level predicted. Galaxies with large circular velocities do indeed lie preferentially in high-density regions. This effect is closely related to the well-known dependence of galaxy clustering on morphological type. The theory predicts that galaxies with circular velocities in excess of 300 km s^-1^ should almost never be found in low-density regions.