Padmanabhan, T.Vasanthi, M. M.2012-03-022012-03-021985-08-12http://hdl.handle.net/11007/106The effect of a perturbing mass on a homogeneous collisionless cloud of dark matter is considered in the linear approximation. It is shown by that gravitational potential can have turning points, in sharp contrast with gravitating system of finite extent. The model offers a reasonable explanation for the observed secondary maxima in the destiny distribution of rich clusters . The relevance of the model to the flatness of the rotation curves of galaxies is also discussed.enDark matterCollisionless-cluster of galaxiesDark matter-galaxiesRotation curvesAstronomyMathematical formArticle