Main and inter-pulse interaction in PSRs J1842+0358 and J1926+0737: evidence of inter-pole communication

Our understanding of the elusive radio-pulsar emission mechanism would be deepened by determining the locality of the emission. Pulsars in which the two poles interact might help us to solve this challenge. We report the discovery of interacting emission between the main and the inter-pulse in two pulsars, J1842+0358 and J1926+0737, based on FAST and MeerKAT data. When the emission is bright in one pulse, it is dim in the other. Even when split into just two groups (strong versus weak), the anti-correlated brightness can change by a factor of ≳2. Both sources furthermore show the same quasi-periodic modulation from the main and inter-pulse at timescales exceeding 100 pulse periods. The longitude stationary modulation from at least one pulse suggests that it is a key signature for inter-pulse pulsars with a main and inter-pulse interaction. If the interaction occurs within an isolated magnetosphere without external influences, either communication between the opposite poles is required, or global changes drive both. This detailed study of these two sources was only made possible by an improved sensitivity. The fact that both show two-pole modulation strongly suggests that this is a general phenomenon in inter-pulse pulsars. In regular pulsars, only one pole is visible, and a number of these regular pulsars show correlated changes between the profile and the spin-down rate that are also thought to be caused by global magnetospheric changes. Our results strengthen the case that these interactive magnetospheres are common to all pulsars.