Outbursts from a Black Hole via Alfven Wave to Electromagnetic Wave Mode Conversion

A new mechanism for outbursts from a black hole is proposed. A recent work on general relativistic plasma equilibria around a black hole has shown the possibility of equilibrium presence of matter and magnetic fields in the neighborhood of the event horizon, even where the corpuscular equilibrium is not allowed ( r < 3 R s , where R s is the Schwarzschild radius). A large-amplitude Alfvén pulse in the black hole electron-positron atmosphere that propagates away from the hole into lower magnetic field regions can experience resonance and mode-convert itself into a large-amplitude electromagnetic (EM) pulse. It is shown theoretically and computationally that through this process a large amount of mass can be picked up by the solitary EM pulse capable of traveling in a vacuum, with which particles are accelerated to relativistic energies. Photon spectra are obtained not inconsistent with observation, which follow a multiple power law with log-log slopes of approximately -1, before a "knee" in the spectrum at energies slightly greater than 1 MeV. It is suggested that this may be a possible mechanism for the outbursts of the black hole binary GRO J1655-40.