Pulse Fluctuation Properties at 35 MHz

Extract

A few bright pulsars were observed at 35 MHz for ≳ 1000s using the Gauribidanur Radio Telescope, and the data were analysed to study their single-pulse fluctuation properties (Asgekar & Deshpande, 1999a; & ref.s therein).

The well-known drifter B0943+10 shows a well resolved two-component profile at 35 MHz. The longitude-resolved fluctuation spectrum (Fig 1) shows a stable phase modulation feature (aliased) at 0.459 c/P₁, consistent with its drifting pattern seen at higher radio-frequencies. Using the “Cartographic Transform” technique (Deshpande & Rankin, 1999; hereafter DR), we have mapped the pattern of its polar emission at 35 MHz (Asgekar & Deshpande, 1999b) as shown in fig 1. Helped by the larger cone radius at lower frequencies, the subbeams can be sampled in their full radial extent at 35 MHz. These results combined with those at higher frequencies (DR) suggest a steadily rotating system consisting of 20 emission-columns in the polar region as that responsible for the observed fluctuations over the entire range of observed frequencies.