Dark matter tomography

Gravitational lensing provides an opportunity to directly image dark matter concentrations. This article is a short review of recent progress in strong and weak gravitational lens tomographic imaging of dark matter. The lens-distorted images of background galaxies are inverted, yielding a 2-D map of the projected dark matter overdensity. The maps cover a range of scales and thus constrain the nature of dark matter. On 10 kpc scales, high resolution strong lens inversions reveal a soft core in the mass distribution, not seen in scale-free cold dark matter n-body simulations. On 10 Mpc scales, statistical weak lensing inversion maps of mass show the outer mass profile of overdensities in the linear regime.