%0 Journal Article
%T Compatible systems of symplectic Galois representations and the inverse Galois problem II. Transvections and huge image
%A Sara Arias-de-Reyna
%A Luis Dieulefait
%A Gabor Wiese
%J Mathematics
%D 2012
%I arXiv
%X This article is the second part of a series of three articles about compatible systems of symplectic Galois representations and applications to the inverse Galois problem. This part is concerned with symplectic Galois representations having a huge residual image, by which we mean that a symplectic group of full dimension over the prime field is contained up to conjugation. A key ingredient is a classification of symplectic representations whose image contains a nontrivial transvection: these fall into three very simply describable classes, the reducible ones, the induced ones and those with huge image. Using the idea of an (n,p)-group of Khare, Larsen and Savin we give simple conditions under which a symplectic Galois representation with coefficients in a finite field has a huge image. Finally, we combine this classification result with the main result of the first part to obtain a strenghtened application to the inverse Galois problem.
%U http://arxiv.org/abs/1203.6552v3