The vacuole model: new terms in the second order deflection of light

Abstract

The present paper is an extension of a recent work (Bhattacharya et al. 2010) to the Einstein-Strauss vacuole model with a cosmological constant, where we work out the light deflection by considering perturbations up to order M3 and confirm the light bending obtained previously in their vacuole model by Ishak et al. (2008). We also obtain another local coupling term −5πM2Λ/8 related to Λ, in addition to the one obtained by Sereno (2008, 2009). We argue that the vacuole method for light deflection is exclusively suited to cases where the cosmological constant Λ disappears from the path equation. However, the original Rindler-Ishak method (2007) still applies even if a certain parameter γ of Weyl gravity does not disappear. Here, using an alternative prescription, we obtain the known term −γR/2, as well as another new local term 3πγM/2 between M and γ. Physical implications are compared, where we argue that the repulsive term −γR/2 can be masked by the Schwarzschild term 2M/R in the halo regime supporting attractive property of the dark matter.

Strong field lensing by Damour-Solodukhin wormhole

“…Light rays passing infinitesimally close to the photon sphere wind up a large number of times before escaping away. While the the theoretical effect of light bending plays the role of core physics (see, e.g., [10,11]), the observable effect of gravitational lensing is a step ahead providing observable set of values that may constitute a kind of "identity card" (name coined by Bozza [12]) for different types of lenses. Since good evidences exist in favor of black holes (e.g., each galaxy is believed to host a black hole in its center), a curious question is to what extent a wormhole can reproduce strong field lensing observables of a Schwarzschild black hole.…”

Constraint on dark matter central density in the Eddington inspired Born-Infeld (EiBI) gravity with input from Weyl gravity

“…Similarly, in Weyl gravity, the first order light deflection angle θ W by a galaxy, first obtained by Edery and Paranjape [89], contains the galactic halo parameter γ appearing in the MO model. Bhattacharya et al [90,91] calculated higher order deflection terms. Strong field lensing in the Weyl gravity has been studied recently in [92], and the predictions can be verified by actual observations in future.…”

Light bending, static dark energy, and related uniqueness of Schwarzschild–de Sitter spacetime

“…Note that this is analogous to the vacuole model of a structure inside the Einstein radius discussed in e.g. [10,22] and references therein, for ΛCDM.…”