$$ \DeclareMathAlphabet{\matheuler}{U}{eus}{m}{n} \newcommand\F{\mathbb F} \newcommand\P{\mathbb P} \newcommand\A{\mathbb A} \newcommand\T{\mathbb T} \newcommand\msO{\mathscr O} \newcommand\msL{\mathscr L} \newcommand\ms{\mathscr} \newcommand\GL{\opname{GL}} \newcommand\eps{\varepsilon} \newcommand\opname{\operatorname} \newcommand\Proj{\opname{Proj}} \newcommand\Pic{\opname{Pic}} \newcommand\hom{\opname H} \newcommand\Char{\opname{char}} \newcommand\Hom{\opname{Hom}} \newcommand\Sel{\opname{Sel}} \newcommand\inv[2][1]{#2^{-#1}} \newcommand\pinv[2][1]{\inv[#1]{\p{#2}}} \newcommand\p[1]{\left(#1\right)} $$

Niven T. Achenjang

Welcome!

I am a math grad student at MIT, broadly interested in arithmetic geometry and especially in points on varieties. My advisor is Bjorn Poonen.

Recently, I have most actively thinking about Brauer groups of stacky curves, but you can find more information on my research in my cv (and probably also under the “news” header below).

I am currently on the job market and am very happy to come talk about my work!

Fun fact: if you press the moon/sun in the top right, you can switch between light/dark themes for this site.

There are many hidden secrets on this site. Try and find them all (seems some of them are less hidden on mobile...).

news

Sep 4, 2024 I attended Oberwolfach’s Explicit Methods in Number Theory workshop, where I gave a talk about some of my recent, ongoing work computing Brauer groups of stacky curves. In particular, I discussed a computation of the Brauer group of a tame stacky curve over an algebraically closed field (unlike in the scheme case, these are often nonzero).
Jul 9, 2024 I gave a lightning talk at MIT’s Mordell conjecture conference on my 2-Selmer work.
Jun 2, 2024 I spoke at GTA: Philadelphia on mine and Jackson Morrow’s paper constructing irreducible divisors \(D\) for which we can prove finiteness of \(D\)-integral points.
Apr 2, 2024 I will be travelling to Seattle to talk in UW’s Number Theory Seminar on work which appeared in my Brauer paper with Deewang, Aash, Caleb, and Rose.
Jan 2024 I gave a talk at JMM this year on my 2-Selmer paper. I will also be talking about it again soon at
Nov 29, 2023 Various coauthors and I posted a new paper on arxiv, in which we compute the Brauer group of the moduli stack \(\mathscr Y_0(2)\) parameterizing elliptic curves equipped with a cyclic subgroup of order \(2\).

publications

  1. ArXiv
    The Brauer Group of \(\mathscr Y_0(2)\)
    Achenjang, Niven, Bhamidipati, Deewang, Jha, Aashraya, Ji, Caleb, and Lopez, Rose
    2023
  2. ArXiv
    The Average Size of 2-Selmer Groups of Elliptic Curves in Characteristic 2
    Achenjang, Niven
    2023
  3. IMRN
    Integral Points on Varieties With Infinite Étale Fundamental Group
    Achenjang, Niven T, and Morrow, Jackson S
    International Mathematics Research Notices,  2023
  4. IJNT
    On gaps in the closures of images of divisor functions
    Achenjang, Niven, and Berger, Aaron
    International Journal of Number Theory,  2019