Revisiting D-branes in $AdS_3 \times S^3$
  We find the most general supergravity solution in an $AdS^3 \times S^3$ background preserving an $AdS_2 \times S^2$ symmetry and half the supersymmetries. Contrary to previous expectations from boundary state arguments, it is shown that no solutions exist containing localized brane sources. 
Jason Kumar, Arvind Rajaraman