  Axions are hypothetical particles related to the violation of the
charge-parity symmetry, being the most prone candidates for dark matter.
Multiple attempts to prove their existence are currently performed in different
physical systems. Here, we anticipate the possibility of the axions coupling to
the electrostatic (Langmuir) modes of a strongly magnetized plasma, by showing
that a new quasi-particle can be defined, the axion-plasmon polariton. The
excitation of axions can be inferred from the pronounced modification of the
dispersion relation of the Langmuir waves, a feature that we estimate to be
accessible in state-of-the-art plasma-based experiments. We further show that,
under extreme density and magnetic field conditions (e.g. at the interior of
dense neutron stars), the axion-plasmon polariton becomes dynamically unstable,
similarly to the case of the Jeans instability occurring in self-gravitating
fluids. This latter result anticipates a plausible mechanism to the creation of
axion-like particles in the universe.

High Energy Physics - Phenomenology;Plasma Physics