Search for interpulses in a complete sample of pulsars at a frequency of 111 MHz

Abstract

An interpulse search was carried out in a sample of 96 pulsars observed on the Large Phased Array (LPA) radio telescope in the Pushchino Multibeams Pulsar Search (PUMPS). The pulsar sample is complete for pulsars having a signal-to-noise ratio (S/N) in the main pulse ($MP$) greater than 40. To search for weak interpulses ($IP$), the addition of average profiles over an interval of up to 10 years was used. Interpulses were detected in 12 pulsars (12.5\% of the sample), of which 7 pulsars have an interpulse located near the $180^o$ phase relative to the main pulse (probable orthogonal rotators), and 5 have phases far from $180^o$ (probable coaxial rotators). The amplitude ratios of $IP/MP$ are in the range of 0.004-0.023, the median value is 0.01. Estimates of the observed number of coaxial and orthogonal rotators with $IP/MP \ge 0.01$ do not contradict the model according to which, during evolution, the magnetic axis and the axis of rotation become orthogonal.