Reversals of Radio Emission Direction in PSR B1822-09

The pulse profile of pulsar B1822-09 exhibits a very peculiar kind of modechanging: a "precursor" appearing just in front of the Main-Pulse (MP) exhibitsperiods of nulling, during which an interpulse (IP) becomes detectable atrotation phase separated by roughly 180 deg from the precursor. We propose thatthis bizarre phenomenon, which requires an information transfer between the twocomponents, occurs by means of reversal of a direction of coherent radioemission generated in the same emission region. This interpretation naturallyexplains the lack of weak radio emission in the off-pulse regions, as well asthe problem of information transfer between emission regions associated withthe MP precursor and the IP. The reversals also imply nulling. The model hasprofound physical implications: (i) the mechanism of coherent radio emissionmust allow radiation into two, opposite, intermittently changing directions;(ii) the radio waves must be able to propagate through inner regions of theneutron star magnetosphere with strong magnetic field. Most importantly, themodel implies inward radio emission in pulsar magnetosphere.Comment: 9 pages, 2 figures, submitted to ApJ Letter