MOND and the lensing Fundamental Plane: No need for dark matter on galaxy scales

TL;DR

This paper shows that the observed properties of elliptical galaxies can be explained by MOND without invoking dark matter, aligning with gravitational lensing data and the fundamental plane.

Contribution

It demonstrates that the galaxy fundamental plane and lensing observations are consistent with MOND, eliminating the need for dark matter on galaxy scales.

Findings

The observed fundamental plane matches the MOND prediction.

Lensing mass within half an effective radius aligns with visible stars plus MOND effects.

No additional dark matter component is required to explain lensing data.

Abstract

Bolton et al. (2007) have derived a mass-based fundamental plane using photometric and spectroscopic observations of 36 strong gravitational lenses. The lensing allows a direct determination of the mass-surface density and so avoids the usual dependence on mass-to-light ratio. We consider this same sample in the context of modified Newtonian dynamics (MOND) and demonstrate that the observed mass-based fundamental plane coincides with the MOND fundamental plane determined previously for a set of high-order polytropic spheres chosen to match the observed range of effective radii and velocity dispersions in elliptical galaxies. Moreover, the observed projected mass within one-half an effective radius is consistent with the mass in visible stars plus a small additional component of ``phantom dark matter'' resulting from the MOND contribution to photon deflection.