A Survey of Dynamical and Gravitational Lensing Tests in Scale Invariance: The Fall of Dark Matter?

TL;DR

This paper reviews the role of scale invariance in physics and presents observational evidence that it can explain various astronomical phenomena traditionally attributed to dark matter, without requiring adjustable parameters.

Contribution

It provides a comprehensive survey of scale-invariant effects in astronomy and demonstrates how they can account for galaxy rotation curves, cluster velocities, and lensing discrepancies without dark matter.

Findings

Scale invariance explains galaxy rotation curves and cluster velocities.

Scale invariance affects inferred mass-to-light ratios in gravitational lensing.

No dark matter or adjustable parameters are needed in the scale-invariant framework.

Abstract

We first briefly review the adventure of scale invariance in physics, from Galileo Galilei, Weyl, Einstein, and Feynman to the revival by Dirac (1973) and Canuto et al. (1977). We then gather concrete observational evidence that scale-invariant effects are present and measurable in astronomical objects spanning a vast range of masses (0.5 M$_{\odot} <$ M $< 10^{14}$ M$_{\odot}$) and an equally impressive range of spatial scales (0.01 pc $<$ r $<$ 1 Gpc). Scale invariance accounts for the observed excess in velocity in galaxy clusters with respect to the visible mass, the relatively flat/small slope of rotation curves in local galaxies, the observed steep rotation curves of high-redshift galaxies, and the excess of velocity in wide binary stars with separations above 3000 kau found in Gaia DR3. Last but not least, we investigate the effect of scale invariance on gravitational lensing. We show that scale invariance does not affect the geodesics of light rays as they pass in the vicinity of a massive galaxy. However, scale-invariant effects do change the inferred mass-to-light ratio of lens galaxies as compared to GR. As a result, the discrepancies seen in GR between the total lensing mass of galaxies and their stellar mass from photometry may be accounted for. This holds true both for lenses at high redshift like JWST-ER1 and at low redshift like in the SLACS sample. Of note is that none of the above observational tests require dark matter or any adjustable parameter to tweak the theory at any given mass or spatial scale.