Gravity balls in induced gravity model— ’gravitational lens’ effects

In non-minimally coupled effective gravity theories one can have non-topological solitonic solutions. A typical solution is a spherical region with Geff = 0 outside and having the canonical Newtonian value inside. Such a spherical domain (gravity-ball) is characterized by an effective index of refraction which causes bending of light incident on it. The gravity ball thus acts as a spherical lens. We consider the gravity ball to be of a size of a typical cluster of galaxies and show that even empty (without matter) gravity ball can produce arc-like images of the background source galaxy. In the case of background random galaxy field the ball produces distortions (‘shear’) of that field. We also obtained constraints on the size of the large gravity ball, which can be inferred from the existing observations of clusters with arcs.