Testing the cold dark matter model with gravitational lensing
The cold dark matter model of structure formation appears to offer the current best description for all the observational data in hand, despite the lack of detection of the putative dark matter particle. Clusters of galaxies are powerful laboratories for testing the standard models versus alternatives. The cold dark matter offers robust predictions for the amount of substructure in collapsed dark matter halos. New results from the tests of the granularity of the dark matter distribution predicted by this model with the recent exquisite data from cluster lenses imaged by the Hubble Space Telescope (HST) will be presented. The detailed distribution of substructure down to 10^9 solar masses can be mapped via gravitational lensing in clusters. And comparison of the observational data with high resolution state-of-the-art simulations of the cold matter model, offers a new, stringent test. Utilizing the substructure derived from the HST Frontier Fields data, comparisons with the Illustris suite of simulations and analytic calculations and their implications suggest that the cold dark matter model is here to stay.