  Motivated by the recent experiment by Marguerite et al. [1] on imaging in
graphene samples, we investigate theoretically the dissipation induced by
resonant impurities in the quantum Hall regime. The impurity induced forward
scattering of electrons at quantum Hall edges leads to an enhanced phonon
emission, which reaches its maximum when the impurity state is tuned to
resonance by a scanning tip voltage. Our analysis of the effect of the tip
potential on the dissipation reveals peculiar thermal rings around the
impurities, in consistency with experimental observations. Remarkably, this
impurity-induced dissipation reveals non-trivial features that are unique for
chiral 1D systems such as quantum Hall edges. First, the dissipation is not
accompanied by the generation of resistance. Second, this type of dissipation
is highly nonlocal: a single impurity induces heat transfer to phonons along
the whole edge.
