  We analytically describe the plasmonic edge modes for an interface that
involves the twisted bilayer graphene (TBG) or other similar Moire van der
Waals heterostructure. For this purpose, we employ a spatially homogeneous,
isotropic and frequency-dependent tensor conductivity which in principle
accounts for electronic and electrostatic interlayer couplings. We predict that
the edge mode dispersion relation explicitly depends on the chiral response
even in the nonretarded limit, in contrast to the collective bulk plasmonic
excitations in the TBG. We obtain a universal function for the dispersion of
the optical edge plasmon in the paramagnetic regime. This implies a
correspondence of the chiral-TBG optical plasmon to a magnetoplasmon of a
single sheet, and chirality is interpreted as an effective magnetic field. The
chirality also opens up the possibility of nearly undamped acoustic modes in
the paramagnetic regime. Our results may guide future near-field nanoscopy for
van der Waals heterostructures. In our analysis, we retain the long-range
electrostatic interaction, and apply the Wiener-Hopf method to a system of
integral equations for the scalar potentials of the two layers.
