  Plasma-filled pulsar magnetospheres contain thin current sheets wherein the
charged particles are accelerated by magnetic reconnections to travel at
ultra-relativistic speeds. On the other hand, the plasma frequency of the more
regular force-free regions of the magnetosphere rests almost precisely on the
upper limit of radio frequencies, with the cyclotron frequency being far higher
due to the strong magnetic field. This combination produces a peculiar
situation, whereby radio-frequency waves can travel at subluminal speeds
without becoming evanescent. The conditions are thus conducive to Cerenkov
radiation originating from current sheets, which could plausibly serve as a
coherent radio emission mechanism. In this paper we aim to provide a portrait
of the relevant processes involved, and show that this mechanism can possibly
account for some of the most salient features of the observed radio signals.
