%0 Journal Article
%T Sifted character sums and free quotients of Bianchi groups
%A Jan-Christoph Schlage-Puchta
%J Mathematics
%D 2011
%I arXiv
%R 10.1017/S0305004106009261
%X We show that the Bianchi group $\mathrm{PSL}_2(\mathcal{O}_d)$, where $\mathcal{O}_d$ is the ring of integers in $\Q(\sqrt{d})$, $d<0$, has a free quotient of rank $\geq |d|^{1/4-\epsilon}$, as $|d|\to\infty$.
%U http://arxiv.org/abs/1105.1453v1