A burst emission mechanism for coherent radiation from pulsars

Various mechanisms for generating coherent curvature radiation have been proposed 1 to explain the high brightness temperature of pulsars at radio frequencies. The bunching of counterstreaming charged particles 2–5 , although requiring rather special conditions and subject to criticism 6 , has hitherto seemed the most plausible. Here we propose an entirely new mechanism of ‘burst emission’, which initiates at the surface of a neutron star and occurs naturally without any need to postulate special conditions. We argue that the induced electric field in the near magnetosphere of a rotating neutron star is sufficiently strong to detach moderately large grains of solid matter from the surface in the polar-cap regions. The detached grains erupt and form ascending plumes or jets of dense and highly charged gas. These thread-like plumes, of length h ≳ 10 2 cm, then accelerate along the open magnetic field lines and emit intense partially coherent radiation, at radio frequencies, with a low-frequency cutoff at c/h . Our estimates indicate that burst emission can account for the principal characteristics of the observed radiation from pulsars at radio frequencies.