  Wave-like dark matter made of spin-1 particles (dark photons) is expected to
form ground state clumps called "vector solitons", which can have different
polarizations. In this work, we consider the interaction of dark photons with
photons, expressed as dimension-6 operators, and study the electromagnetic
radiation that arises from an isolated vector soliton due to parametric
resonant amplification of the ambient electromagnetic field. We characterize
the directional dependence and polarization of the outgoing radiation, which
depends on the operator as well as the polarization state of the underlying
vector soliton. We discuss the implications of this radiation for the stability
of solitons and as a possible channel for detecting mergers of vector solitons
through astrophysical observations.
