Repulsive gravitational forces: a possible mechanism for clustering.
Abstract
It is well known that in a homogeneous cosmological universe, a positive cosmological constant induces repulsive forces. The paper shows that in a locally inhomogeneous cosmological model, these repulsive forces are related to the sign of q, the deceleration parameter of the associated cosmological space, and to the sign of the apparent mass of the central perturbation (which can be negative with a positive energy density everywhere). When q is almost zero  crossing the value zero  small random perturbations of the matter density are the sources of a gravitational instability which can generate a mechanism of fragmentation in an a priori homogeneous universe.
 Publication:

The Astrophysical Journal
 Pub Date:
 January 1977
 DOI:
 10.1086/154899
 Bibcode:
 1977ApJ...211...16E
 Keywords:

 Cosmology;
 Gravitation Theory;
 Gravitational Effects;
 Relativity;
 Astronomical Models;
 Field Theory (Physics);
 Universe;
 Astrophysics