  Primary charges multiply in the magnetosphere of neutron stars by
electromagnetic cascade. This is accounted for the first time when computing
the flux generated by axion-photon resonance, noting: (i) axions of up to
dozens of meV of mass mix in the magnetized plasma; (ii) radio signal from
isolated stars of inferable multiplicity factor is undetectable, which could
extend up to infrared; (iii) observation of Galactic populations is also
unpromising, as the boost is exiguous; (iv) telescopes could yet be sensitive
to gravitational focusing of dark matter, e.g., SGR 1745-2900 orbiting Sgr A*.

High Energy Physics - Phenomenology;High Energy Astrophysical Phenomena