A. Ash, GALOIS REPRESENTATIONS AND HECKE OPERATORS ASSOCIATED WITH THE MOD-P COHOMOLOGY OF GL(1,Z) AND GL(2,Z), Proceedings of the American Mathematical Society, 125(11), 1997, pp. 3209-3212
We prove that any Hecke eigenclass in the mod p cohomology of a congru
ence subgroup of GL(1,Z) or GL(2,Z) has attached to it a mod p Galois
representation such that the characteristic polynomial of a Frobenius
element at a prime l equals the Hecke polynomial at l.