Astrophysical and Cosmological Constraints on a Scale-Dependent Gravitational Coupling

We study the phenomenological consequences of the recently proposed idea of a running gravitational coupling on macroscopic scales. When applied to the rotation curves of galaxies, we find that their flatness requires the presence of baryonic dark matter. Bounds on the variation of the gravitational coupling from primordial nucleosynthesis and the change of the period of binary pulsars are analysed. We also study constraints on the variations of G with scale from gravitational lensing and the cosmic virial theorem, as well as briefly discuss the implications of such a scenario for structure formation. CERN--TH/95-15 1 On leave of absence from Departamento de F'isica, Instituto Superior T'ecnico, Av. Rovisco Pais, 1096 Lisboa Codex, Portugal; also at Theory Division, CERN; E-mail: Orfeu@vxcern.cern.ch 2 PPARC postdoctoral research fellow. E-mail: j.bellido@sussex.ac.uk 1 Introduction The flatness of the rotation curves of galaxies and the large structure of the Universe indicate t..