Radio emission features in different modes of PSR J0826+2637 (B0823+26)

We report on a detailed analysis of the radio emission during the different modes of the pulsar J0826+2637 (B0823+26), observed using the Giant Meterwave Radio Telescope at 306-339 MHz observing frequencies. The pulsar profile has a post-cursor and interpulse emission in addition to the main pulse. The single pulses showed the presence of nulling, periodic fluctuation in the emission as well as two prominent modes. In addition the pulsar also showed the presence of a null state where no emission was seen for roughly an hour which was immediately followed by a short duration (∼5 min) bright state termed the Q-bright state. The nulling varied significantly in the two modes, from a few per cent nulls in B mode to more than 90 per cent nulling during the Q mode. Additionally, the pulsar showed the presence of low-level emission in both the interpulse and post-cursor components when the main pulse nulled in B mode. We detected periodic fluctuations in both the main pulse and post-cursor during B mode which were most likely a form of periodic amplitude modulation unrelated to subpulse drifting. We have also detected the appearance of periodicity during the transitions from the null to the burst states in the Q mode, which was longer than the B mode modulations. Our analysis further revealed a significant increase in the main pulse and post-cursor intensity during the transition from the Q mode to the short duration Q-bright mode. On the other hand no commensurate variation was visible in the interpulse intensity.