Finite maximal orientation reversing group actions on handlebodies and 3-manifolds

We study arbitrary (that is not necessarily orientation preserving) finite group actions on 3-dimensional orientable or nonorientable handlebodies of genus g. For g>1, the maximal possible order is 24(g−1); we characterize the corresponding groups of this order and also the occuring quotient orbifolds. Then we use this to study finite group actions of large order (with respect to the equivariant Heegaard genus g) on closed 3-manifolds, again concentrating on the maximal case of order 24(g−1). Our results extend corresponding results in the orientation preserving setting. Whereas for arbitrary finite group actions on handlebodies much more types of quotient orbifolds occur than in the orientation preserving case, it turns out that for closed 3-manifolds the situation is quite rigid, in contrast to the orientation preserving case where one has many possibilities to construct manifolds with large group actions.