Can TeVeS avoid Dark Matter on galactic scales?

Abstract

A fully relativistic analysis of gravitational lensing in TeVeS is presented. By estimating the lensing masses for a set of six lenses from the CASTLES database, and then comparing them to the stellar mass, the deficit between the two is obtained and analysed. Considering a parametrised range for the TeVeS function $mu(y)$, which controls the strength of the modification to gravity, it is found that on galactic scales TeVeS requires additional dark matter with the commonly used $mu(y)$. A soft dependence of the results on the cosmological framework and the TeVeS free parameters is discussed. For one particular form of $mu(y)$, TeVeS is found to require very little dark matter. This choice is however ruled out by rotation curve data. The inability to simultaneously fit lensing and rotation curves for a single form of $mu(y)$ is a challenge to a "no dark matter" TeVeS proposal.