We give a short proof of a theorem of Handel and Mosher  stating that any finitely generated subgroup of Out either contains a fully irreducible automorphism, or virtually fixes the conjugacy class of a proper free factor of , and we extend their result to non finitely generated subgroups of Out.
Cite this article
Camille Horbez, A short proof of Handel and Mosher's alternative for subgroups of Out. Groups Geom. Dyn. 10 (2016), no. 2, pp. 709–721DOI 10.4171/GGD/361