Taylor coefficients of Anderson generating functions and Drinfeld torsion extensions

Abstract

We generalize our work on Carlitz prime power torsion extension to torsion extensions of Drinfeld modules of arbitrary rank. As in the Carlitz case, we give a description of these extensions in terms of evaluations of Anderson generating functions and their hyperderivatives at roots of unity. We also give a direct proof that the image of the Galois representation attached to the [Formula: see text]-adic Tate module lies in the [Formula: see text]-adic points of the motivic Galois group. This is a generalization of the corresponding result of Chang and Papanikolas for the [Formula: see text]-adic case.