Confronting MOND and TeVeS with strong gravitational lensing over galactic scales: an extended survey

TL;DR

This study tests modified gravity theories MOND and TeVeS against strong gravitational lensing data at galactic scales, finding that additional dark matter components are needed, challenging these theories' viability as alternatives to dark matter.

Contribution

It extends previous lensing analyses by comparing lensing and stellar masses in nine systems, exploring various interpolating functions within MOND/TeVeS, and assessing their consistency with observations.

Findings

Five systems show significant excess lensing mass over stellar mass.

One system (Q0957) may be explained by hot neutrino components.

Four systems require cold dark matter even in modified gravity frameworks.

Abstract

The validity of MOND and TeVeS models of modified gravity has been recently tested by using lensing techniques, with the conclusion that a non-trivial component in the form of dark matter is needed in order to match the observations. In this work those analyses are extended by comparing lensing to stellar masses for a sample of nine strong gravitational lenses that probe galactic scales. The sample is extracted from a recent work that presents the mass profile out to a few effective radii, therefore reaching into regions that are dominated by dark matter in the standard (general relativity) scenario. A range of interpolating functions are explored to test the validity of MOND/TeVeS in these systems. Out of the nine systems, there are five robust candidates with a significant excess (higher that 50%) of lensing mass with respect to stellar mass, irrespective of the stellar initial mass function. One of these lenses (Q0957) is located at the centre of a galactic cluster. This system might be accommodated in MOND/TeVeS via the addition of a hot component, like a 2 eV neutrino, that contribute over cluster scales. However, the other four robust candidates (LBQS1009, HE1104, B1600, HE2149) are located in field/group regions, so that a cold component (CDM) would be required even within the MOND/TeVeS framework. Our results therefore do not support recent claims that these alternative scenarios to CDM can survive astrophysical data.