Light bending as a probe of the nature of dark energy

Abstract

We study the bending of light for static spherically symmetric (SSS) space-times which include a dark energy contribution. Geometric dark energy models generically predict a correction to the Einstein angle written in terms of the distance to the closest approach, whereas a cosmological constant Λ does not. While dark energy is associated with a repulsive force in cosmological context, its effect on null geodesics in SSS space-times can be attractive as for the Newtonian term. This dark energy contribution may be not negligible with respect to the Einstein prediction in lensing involving clusters of galaxies. Strong lensing may therefore be useful to distinguish Λ from other dark energy models.PACS numbers: 95.36.+x,95.30.Sf,04.50.+h

Contribution of the cosmological constant to the relativistic bending of light revisited

“…in agreement with footnote [9] in [13] and, for Λ = 0, it reduces to equation (6.3.37) that was derived for Schwarzschild in [17]. Now, if one chooses to express the Weyl focusing fully in terms of the point of closest approach r0 then using (23) in order to substitute for h 2 …”

“…The argument for the non-influence of Λ was apparently first made in [9] and has been re-made and reaffirmed by other authors, see for example [10,11,12,13,14]. The common basis of their arguments is that, in the Schwarzschild-de Sitter metric (first derived by Kottler [15]), which applies when Λ is included, Λ nevertheless drops out of the exact r, φ differential equation for a light path (null geodesic).…”

CMB polarization systematics, cosmological birefringence, and the gravitational waves background

“…1 As counterexample see [17,22] 2 Circular polarization often neglected since not expected in the standard scenario where t labels time, K is the detector gain,γ the observed sky direction 3 , n is the detector noise, δ is the angle between the telescope reference frame and a meridian in the sky, and ε and β are the polarimeter properties, so defined:…”

“…However, since the seminal paper by Carroll et al ([12]) the possibility of a cosmological birefringence, or in vacuo rotation of the polarization direction of a photon, has been considered by several authors (see e.g. [13,14,15,16,17,18,19,20,21] and references therein). Even if exotic, cosmological birefringence is therefore predicted by a wide class of non-standard models and provides information on symmetry violations and on pseudoscalar fields beyond the standard model.…”

A constraint on Planck-scale modifications to electrodynamics with CMB polarization data

“…[14,15,16,17,18,19]) the relevance of CMB polarization data for testing birefringence, and some studies have motivated the analysis also from a broadly-intended quantum-gravity perspective [17,20],but there is still no dedicated study attempting to establish whether the sensitivity levels provided by CMB observations could provide access to birefringence introduced at the Planck energy scale. Here, we make this connection clear and provide a constraint using existing BOOMERanG and WMAP polarization data.…”