Parallel sessions

In this session we will bring together observers and simulators working with gravitational lenses in order to take stock of our present understanding of dark matter substructure, identify gaps in our knowledge, and prepare for the rich new datasets that will soon be on the horizon.

The distribution of dark matter on galaxy to cluster scales plays an important role in many aspects of Astronomy. Yet there are currently significant tensions between our theoretical understanding of this "substructure" and the picture we derive from observations. With the ability to probe dark (and baryonic) matter over a wide range of physical sizes and mass ranges, gravitational lensing is a particularly powerful and efficient tool for investigating these discrepancies. Adding to that, with current and upcoming missions (such as HST, JWST, Euclid, ALMA, SDSS-V, DESI, LSST, and the ELT) expected to find hundreds of thousands of new cluster and galaxy-galaxy lenses, now is the perfect time to address these problems head-on.

By combining this wealth of data with the latest dark matter and hydrodynamical cosmological simulations of our Universe, we can now hope to measure precise cosmological parameters and test the Lambda-CDM paradigm in a competitive way, all while tracing galaxy clusters’ distribution of substructures and 3D assembly history, the "smooth" shape of individual galaxy halos and their satellites, and even the self-interacting nature of dark matter itself.