  Atomic collapse in graphene nanoribbons behaves in a fundamentally different
way as compared to monolayer graphene, due to the presence of multiple energy
bands and the effect of edges. For armchair nanoribbons we find that bound
states gradually transform into atomic collapse states with increasing impurity
charge. This is very different in zig-zag nanoribbons where multiple
quasi-one-dimensional \emph{bound states} are found that originates from the
zero energy zig-zag edge states. They are a consequence of the flat band and
the electron distribution of these bound states exhibits two peaks. The lowest
energy edge state transforms from a bound state into an atomic collapse
resonance and shows a distinct relocalization from the edge to the impurity
position with increasing impurity charge.
