Indefinitely Flat Circular Velocities and the Baryonic Tully-Fisher Relation from Weak Lensing

TL;DR

This paper uses a new weak lensing deprojection method to show that galaxy circular velocities remain flat out to 1 Mpc, aligning with the Baryonic Tully-Fisher Relation and suggesting a universal galaxy behavior.

Contribution

Introduces a novel deprojection formula for weak lensing to extend galaxy rotation curve analysis beyond traditional limits.

Findings

Circular velocity curves remain flat up to 1 Mpc.

Results agree with the Baryonic Tully-Fisher Relation.

Universal behavior observed across galaxy types.

Abstract

We use a new deprojection formula to infer the gravitational potential around isolated galaxies from weak gravitational lensing. The results imply circular velocity curves that remain flat for hundreds of kpc, greatly extending the classic result from 21 cm observations. Indeed, there is no clear hint of a decline out to 1 Mpc, well beyond the expected virial radii of dark matter halos. Binning the data by mass reveals a correlation with the flat circular speed that closely agrees with the Baryonic Tully-Fisher Relation known from kinematic data. These results apply to both early and late type galaxies, indicating a common universal behavior.