The Cosmological Constant and the Gravitational Light Bending

TL;DR

This paper investigates how the cosmological constant influences gravitational light bending in a Schwarzschild-de Sitter spacetime, showing that it causes measurable corrections to lensing mass estimates at cosmological scales.

Contribution

It provides a detailed analysis of light deflection including the cosmological constant's effects, confirming previous findings and quantifying the correction on lensing masses.

Findings

Corrections due to the cosmological constant are about 2% on average.

The leading correction depends on the cosmological constant, impact parameter, and source distance.

The study refines mass estimates for gravitational lens systems at cosmological distances.

Abstract

The solution of the null non-radial geodesic in a Schwarzschild-de Sitter background is revisited. The gravitational bending of a light ray is affected by the cosmological constant, in agreement with the findings of some previous investigations. The present study confirms that the leading correction term depends directly not only on the cosmological constant but also on the impact parameter and on the angular distance to the source. Using the resulting lens equation, the projected mass of the lens was estimated for several systems displaying Einstein rings. Corrections on masses due to the cosmological constant are, on the average, of the order of 2%, indicating that they are not completly negligible for lens systems at cosmological distances.