The survival of dark matter halos in the cluster Cl 0024 + 16

Theories of structure formation in a cold dark matter dominated Universe predict that massive clusters of galaxies assemble from the hierarchical merging of lower mass subhalos. Exploiting strong and weak gravitational lensing signals inferred from panoramic Hubble Space Telescope imaging data, we present a high resolution reconstruction of the mass distribution in the massive, lensing cluster Cl 0024+16 at z = 0.39. Applying galaxy-galaxy lensing techniques we track the fate of dark matter subhalos as a function of projected cluster-centric radius out to 5 Mpc, well beyond the virial radius. We report the first detection of the statistical lensing signal of dark matter subhalos associated with late-type galaxies in clusters. The mass of a fiducial dark matter halo that hosts an early type L galaxy varies from M = 6.3 −2.0 × 10 11 M⊙ within r < 0.6 Mpc, 1.3 +0.8 −0.6 × 10 M⊙ within r < 2.9 Mpc and increases further to M = 3.7 +1.4 −1.1 × 10 12 M⊙ in the outskirts. The mass of a typical dark matter subhalo that hosts an L galaxy increases with projected cluster-centric radius in line with expectations