On families of elliptic curves $E_{p,q}:y^2=x^3-pqx$ that intersect the same line $L_{a,b}:y=\frac{a}{b}x$ of rational slope
Eldar Sultanow, Anja Jeschke, Amir Darwish Tfiha, Madjid Tehrani, William J Buchanan
TL;DR
The paper investigates when curves E_{p,q}: y^2 = x^3 − pqx, with p<q primes, intersect a fixed rational-slope line L_{a,b}: y = (a/b)x, by reducing the problem to divisibility patterns of 4pqb^4 and isolating six viable cases from sixty total divisor-splits. It then visualizes, for p,q ≤ 6997, the resulting arithmetic structures as arc, tile, or sparse patterns, providing concrete sample curves and explaining observed shapes through number-theoretic principles (e.g., primes of the form a^2 + b^4, representations of pq, and congruence constraints). The six cases connect to broader topics such as Friedlander–Iwaniec primes, sums of squares and fourth powers, and prime-gap heuristics, framing a visually-guided approach to identifying primes that yield rational points on E_{p,q}. The work highlights both promising avenues for locating positive-rank instances and the limitations imposed by deep conjectures in number theory, suggesting future exploration of fixed lines, fixed curves, and refined distributional analyses of prime pairs.
Abstract
Let $p$ and $q$ be two distinct odd primes, $p<q$ and $E_{p,q}:y^2=x^3-pqx$ be an elliptic curve. Fix a line $L_{a.b}:y=\frac{a}{b}x$ where $a\in \mathbb{Z},b\in \mathbb{N}$ and $(a,b)=1$. We study sufficient conditions that $p$ and $q$ must satisfy so that there are infinitely many elliptic curves $E_{p,q}$ that intersect $L_{a,b}$.
