Functoriality and the Inverse Galois problem II: groups of type B_n and G_2

Khare, Chandrashekhar; Larsen, Michael; Savin, Gordan

Functoriality and the Inverse Galois problem II: groups of type B_n and G_2

Authors

Khare, Chandrashekhar

Larsen, Michael

Savin, Gordan

Description

For every finite field F and every positive integer r, there exists a finite extension F' of F such that either SO(2r+1,F') or its simple derived group can be realized as a Galois group over Q. If the characteristic of F is 3 or 5 (mod 8), then we can guarantee that the derived group of SO(2r+1,F') can be realized. Likewise, for every finite field F, there exists a finite extension F' of F such that the finite simple group G_2(F') can be realized a Galois group over Q. The proof uses automorphic forms to construct Galois representations which cut out Galois extensions of the desired type.
25 pages