Microstructure in Radio Emission of the Pulsar B1133+16 at a Frequency of 111 MHz

Abstract

This study is based on observations of the pulsar B1133+16 conducted on the BSA PRAO antenna array at a frequency of 111 MHz with continuous recording of undetected signal (voltage) in the 2.5 MHz band, providing time resolution 0.2 µs. From 30 observation sessions, 570 strong pulses were selected for the subsequent analysis of microstructure parameters. The analysis was performed by computing autocorrelation functions separately for the three components of the mean profile: two extreme main components I and II and for the central weak component \(S\) in the profile saddle. For the component \(S\), microstructure analysis was performed for the first time. Distributions have been constructed by the following parameters: time scales \({{\tau }_{\mu }}\), modulation depth \({{m}_{\mu }}\), and parameter \(d\), which characterizes the shape of the micropulses. Noticeable differences were found in some parameters for different profile components. The discovered features were interpreted in the model of hollow cone with a central component. It was believed that the radio emission of the extreme components (I and II) is generated by ordinary mode O, and the radio emission of the central component is provided by extraordinary mode X. Under this interpretation the radio emission output heights above the polar cap, were estimated to be 45 and 280 km for the X and O modes, respectively. A noticeable deformation of the X mode emission cone relative to the central component S was mentioned. Considerations are presented that point to the spatial structure of the secondary plasma flow, elongated along the meridians of the magnetic field.