The nature of pulsar radio emission

High-quality averaged radio profiles of some pulsars exhibit double, highly symmetric features both in emission and absorption. It is shown that both types of features are produced by a split-fan beam of extraordinary-mode curvature radiation (CR) that is emitted/absorbed by radially-extended streams of magnetospheric plasma. With no emissivity in the plane of the stream, such a beam produces bifurcated emission components (BFCs) when our line of sight passes through the plane. A distinct example of double component created in that way is present in averaged profile of the 5 ms pulsar J1012+5307. We show that the component can indeed be very well fitted by the textbook formula for the non-coherent beam of curvature radiation in the polarisation state that is orthogonal to the plane of electron trajectory. The observed width of the BFC decreases with increasing frequency at the rate that confirms the curvature origin. Likewise, the double absorption features (double notches) are produced by the same beam of the extraordinary-mode CR, when it is eclipsed by thin plasma streams. The intrinsic property of CR to create bifurcated fan beams explains the double features in terms of very natural geometry and implies the curvature origin of pulsar radio emission. (abbreviated)