Average Frobenius distribution for the degree two primes of a number field

Let $K$ be a number field and $r$ an integer. Given an elliptic curve $E$, defined over $K$, we consider the problem of counting the number of degree two prime ideals of $K$ with trace of Frobenius equal to $r$. Under certain restrictions on $K$, we show that "on average" the number of such prime ideals with norm less than or equal to $x$ satisfies an asymptotic identity that is in accordance with standard heuristics. This work is related to the classical Lang-Trotter conjecture and extends the work of several authors

On the number of Mordell-Weil generators for cubic surfaces

Let S be a smooth cubic surface over a field K. It is well-known that new K-rational points may be obtained from old ones by secant and tangent constructions. A Mordell-Weil generating set is a subset B of S(K) of minimal cardinality which generates S(K) via successive secant and tangent constructions. Let r(S,K) be the cardinality of such a Mordell-Weil generating set. Manin posed what is known as the Mordell-Weil problem for cubic surfaces: if K is finitely generated over its prime subfield then r(S,K) is finite. In this paper, we prove a special case of this conjecture. Namely, if S contains two skew lines both defined over K then r(S,K) = 1. One of the difficulties in studying the secant and tangent process on cubic surfaces is that it does not lead to an associative binary operation as in the case of elliptic curves. As a partial remedy we introduce an abelian group H_S(K) associated to a cubic surface S/K, naturally generated by the K-rational points, which retains much information about the secant and tangent process. In particular, r(S, K) is large as soon as the minimal number of generators of H_S(K) is large. In situations where weak approximation holds, H_S has nice local-to-global properties. We use these to construct a family of smooth cubic surfaces over the rationals such that r(S,K) is unbounded in this family. This is the cubic surface analogue of the unboundedness of ranks conjecture for elliptic curves

On Elliptic Curves, Modular Forms, and the Distribution of Primes

In this thesis, we present four problems related to elliptic curves, modular forms, the distribution of primes, or some combination of the three. The first chapter surveys the relevant background material necessary for understanding the remainder of the thesis. The four following chapters present our problems of interest and their solutions. In the final chapter, we present our conclusions as well as a few possible directions for future research. Hurwitz class numbers are known to have connections to many areas of number theory. In particular, they are intimately connected to the theory of binary quadratic forms, the structure of imaginary quadratic number fields, the theory of elliptic curves, and the theory of modular forms. Hurwitz class number identities of a certain type are studied in Chapter 2. To prove these identities, we demonstrate three different techniques. The first method involves a relation between the Hurwitz class number and elliptic curves, while the second and third methods involve connections to modular forms. In Chapter 3, we explore the construction of finite field elements of high multiplicative order arising from modular curves. The field elements are constructed recursively using the equations that Elkies discovered to describe explicit modular towers. Using elementary techniques, we prove lower bounds for the orders of these elements. Prime distribution has been a central theme in number theory for hundreds of years. Mean square error estimates for the Chebotarëv Density Theorem are proved in Chapter 4. These estimates are related to the classical Barban-Davenport-Halberstam Theorem and will prove to be indispensable for our work in Chapter 5, where we take up the study of the Lang-Trotter Conjecture \u27on average\u27 for elliptic curves defined over number fields. We begin Chapter 4 by proving upper bounds on the mean square error in Chebotarëv\u27s theorem. It is this upper bound which features as a key ingredient in Chapter 5. As another application of this upper bound, we continue in Chapter 4 to prove an asymptotic formula for the mean square error. In Chapter 5, we turn to the discussion of the Lang-Trotter Conjecture for number fields \u27on average.\u27 The Lang-Trotter Conjecture is an important conjecture purporting to give information about the arithmetic of elliptic curves, the distribution of primes, and GL(2)-representations of the absolute Galois group. In this chapter, we present some results in support of the conjecture. In particular, we show that the conjecture holds in an average sense when one averages over all elliptic curves defined over a given number field

Dynamically Distinguishing Polynomials

A polynomial with integer coefficients yields a family of dynamical systems indexed by primes as follows: For any prime p, reduce its coefficients mod p and consider its action on the field FpFp. We say a subset of Z[x]Z[x] is dynamically distinguishable mod p if the associated mod pdynamical systems are pairwise non-isomorphic. For any k,M∈Z\u3e1k,M∈Z\u3e1, we prove that there are infinitely many sets of integers MM of size M such that {xk+m∣m∈M}{xk+m∣m∈M} is dynamically distinguishable mod p for most p (in the sense of natural density). Our proof uses the Galois theory of dynatomic polynomials largely developed by Morton, who proved that the Galois groups of these polynomials are often isomorphic to a particular family of wreath products. In the course of proving our result, we generalize Morton’s work and compute statistics of these wreath products

Dynamically Distinguishing Polynomials

A polynomial with integer coefficients yields a family of dynamical systems indexed by primes as follows: For any prime p, reduce its coefficients mod p and consider its action on the field FpFp. We say a subset of Z[x]Z[x] is dynamically distinguishable mod p if the associated mod pdynamical systems are pairwise non-isomorphic. For any k,M∈Z\u3e1k,M∈Z\u3e1, we prove that there are infinitely many sets of integers MM of size M such that {xk+m∣m∈M}{xk+m∣m∈M} is dynamically distinguishable mod p for most p (in the sense of natural density). Our proof uses the Galois theory of dynatomic polynomials largely developed by Morton, who proved that the Galois groups of these polynomials are often isomorphic to a particular family of wreath products. In the course of proving our result, we generalize Morton’s work and compute statistics of these wreath products