Gravitational lensing due to dark matter modelled by vector field

TL;DR

This paper models dark matter as a vector field to analyze gravitational lensing, revealing a constant light deflection angle and an effective deflecting mass greater than the dark matter mass, with edge effects considered.

Contribution

It introduces a vector field model for dark matter that reproduces observed gravitational lensing effects and calculates the impact of halo edges on light deflection.

Findings

Constant deflection angle at small impact distances

Effective deflecting mass is π/2 times the dark matter mass

Halo edge perturbation effects are evaluated

Abstract

The specified constant 4-vector field reproducing the spherically symmetric stationary metric of cold dark matter halo in the region of flat rotation curves results in a constant angle of light deflection at small impact distances. The effective deflecting mass is factor $\pi/2$ greater than the dark matter mass. The perturbation of deflection picture due to the halo edge is evaluated.