Published online by Cambridge University Press: 05 November 2020
Let G be a semisimple real algebraic group defined over
${\mathbb {Q}}$
,
$\Gamma $
be an arithmetic subgroup of G, and T be a maximal
${\mathbb {R}}$
-split torus. A trajectory in
$G/\Gamma $
is divergent if eventually it leaves every compact subset. In some cases there is a finite collection of explicit algebraic data which accounts for the divergence. If this is the case, the divergent trajectory is called obvious. Given a closed cone in T, we study the existence of non-obvious divergent trajectories under its action in
$G\kern-1pt{/}\kern-1pt\Gamma $
. We get a sufficient condition for the existence of a non-obvious divergence trajectory in the general case, and a full classification under the assumption that
$\mathrm {rank}_{{\mathbb {Q}}}G=\mathrm {rank}_{{\mathbb {R}}}G=2$
.