« Galactic scaling relations out to hundreds of kpc from weak lensing »
The dynamical properties of galaxies exhibit strong regularities such as the Baryonic Tully-Fisher Relation and the Radial Acceleration Relation (RAR). The RAR relates the baryonic Newtonian acceleration $g_ »bar »$ and the observed total acceleration $g_ »obs »$ which includes the effects of dark matter. Recently, it was shown that weak-lensing observations allow to probe the RAR of isolated galaxies down to extremely small accelerations $g_ »bar »$, corresponding to many hundreds of $ »kpc »$. I will introduce this weak-lensing RAR and discuss its most recent iteration which features improved stellar masses, a stricter isolation criterion, and a novel deprojection method. The lensing RAR smoothly continues the kinematic RAR by about 2.5 dex in $g_ »bar »$, implying flat rotation curves out to hundreds of $ »kpc »$. I will discuss how this relation constrains models of dark matter and modified gravity.