Smeared end-of-the-world branes

We uncover new nonsupersymmetric 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 <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:msub><a:mrow><a:mi>AdS</a:mi></a:mrow><a:mrow><a:mn>5</a:mn></a:mrow></a:msub><a:mo>×</a:mo><a:msup><a:mi mathvariant="double-struck">S</a:mi><a:mn>5</a:mn></a:msup></a:mrow></a:math> vacuum ends on an <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"><d:mi>S</d:mi><d:mi>O</d:mi><d:mo stretchy="false">(</d:mo><d:mn>6</d:mn><d:mo stretchy="false">)</d:mo></d:math>-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.