Smeared end-of-the-world branes

We uncover new non-supersymmetric boundary conditions in 10- and 11-dimensional supergravity whereby spacetime ends on a smeared distribution of D- and M-branes respectively. For example, we find a solution of type IIB supergravity where the AdS${}_5\times {\mathbb{S}}^5$ vacuum ends on an $SO(6)$-invariant distribution of D3-branes. These distributions give a stringy completion of simple models of tensionful end-of-the-world branes considered previously in the literature. However we find that our solutions are all unstable to the fragmentation of the end-of-the-world brane into its constituents.