Homological representations of low genus mapping class groups

Abstract

Given a finite group $G$ acting on a surface $S$, the centralizer of G in the mapping class group $\text{Mod}(S)$ has a natural representation given by its action on the homology $H_1(S;\mathbb{Q})$. We consider the question of whether this representation has arithmetic image. Several authors have given positive and negative answers to this question. We give a complete answer when S has genus at most 3.

31 pages, 8 figures. Minor edits, final version