On the topological dimension of the Gromov boundaries of some hyperbolic   $Out(F_N)$-graphs
  We give upper bounds, linear in rank, to the topological dimensions of the Gromov boundaries of the intersection graph, the free factor graph and the cyclic splitting graph of a finitely generated free group. 
Mladen Bestvina, Camille Horbez, and Richard D. Wade
math.GR math.GT