Dynatomic Galois groups for a family of quadratic rational maps

For every nonconstant rational function Formula: see text, the Galois groups of the dynatomic polynomials of Formula: see text encode various properties of Formula: see text are of interest in the subject of arithmetic dynamics. We study here the structure of these Galois groups as Formula: see text varies in a particular one-parameter family of maps, namely, the quadratic rational maps having a critical point of period 2. In particular, we provide explicit descriptions of the third and fourth dynatomic Galois groups for maps in this family.