Sparse equidistribution of hyperbolic orbifolds associated to real quadratic fields

Associated to class groups of real quadratic fields, Duke, Imamoglu, and Tóth have defined certain hyperbolic orbifolds and showed that they equidistribute when projected to the modular curve. In this talk I will describe (and show pictures of) an extension of their construction and results to modular curves of higher level as well as sparse subsets of the class groups.

This is joint work with Peter Humphries.