On Elliptic Units and Class Number of a Certain Non-Galois Number Field.
We compute equations for the families of elliptic curves 9-congruent to a given elliptic curve. We use these to find infinitely many non-trivial pairs of 9-congruent elliptic curves over ℚ, i.e. pairs of non-isogenous elliptic curves over ℚ whose 9-torsion subgroups are isomorphic as Galois modules.
This paper focuses on the Diophantine equation , with fixed α, p, and M. We prove that, under certain conditions on M, this equation has no non-trivial integer solutions if , where is an effective constant. This generalizes Theorem 1.4 of the paper by Bennett, Vatsal and Yazdani [Compos. Math. 140 (2004), 1399-1416].