Speaker
Description
Weak gravitational lensing is a crucial tool to measure the mass profiles of dark matter halos. I will discuss a recent weak-lensing analysis of isolated galaxies in KiDS DR4 that finds flat circular velocities out to very large galactocentric radii (at least 300kpc), suggesting that the dark matter halos of galaxies are more extended than expected. Futhermore, these dark matter profiles exhibit scaling relations such as the Baryonic Tully-Fisher Relation that highlight a strong connection between between the visible and dark matter. These results apply to both early and late type galaxies, indicating a common universal behavior. This analysis is enabled by a novel non-parametric deprojection technique that, unlike many existing methods, does not assume a specific mass profile. I show how this non-parametric technique can be extended to galaxy clusters, enabling mass measurements that significantly reduce major sources of bias such as biases from miscentering and baryonic effects. With future observations, this may enable direct, non-parametric measurements of the splashback radius, allowing to discriminate between different models of dark matter and modified gravity.
