2008MNRAS.383.1538B

We report new results obtained from multifrequency observations of PSR B0826-34 with the Giant Metre-wave Radio Telescope (GMRT). (1) We find no evidence of weak emission during the typical long null state of this pulsar, simultaneously at 303 and 610 MHz, as well as individually at 157, 325, 610 and 1060 MHz at separate epochs. Our limit of non-detection is at ∼1 per cent or better of the peak of the active state profile, and corresponds to ∼2 mJy at 610 MHz. (2) Significant correlation in the total intensity of the individual pulses between 303 and 610 MHz is reported from the simultaneous dual-frequency observations, which is indicative of the broad-band nature of the emission. We also report correlation between total energy in the main pulse and interpulse region from the high-sensitivity single-frequency observations at 610 and 1060 MHz. (3) Though we find the drift pattern to be very similar in the simultaneous 303- and 610-MHz data, we observe that the drift band separation (P₂) evolves significantly between these two frequencies, and in a manner opposite to the average profile evolution. In addition, we confirm the dependence of P₂ on pulse longitude at 303 MHz and find indications for the same at 610 MHz. We also present results for subpulse width (ΔΦ_s) at different frequencies, and as well as a function of pulse longitude. (4) As a natural outcome of the simultaneous dual-frequency observations, we obtain an accurate dispersion measure value, equal to 52.2(6) pc/cm3, for this pulsar.