Study On Polarization Characteristics Of Pulsar

Pulsar is one of the research hotspots in Astrophysics in recent years.Many studies based on pulsar are carried out from the average pulse profile and the corresponding polarization characteristics.At the same time,some pulsars with high radiation intensity are also considered to carry out the corresponding research work from single-pulse.The average pulse profile of some pulsars is found to change in a certain period,and some signals disappear.These phenomena are called mode change and null.The research content of this thesis is to study the polarization characteristics of the average pulse profile of some pulsars based on the data observed and published by FAST.At the same time,it also considers the mode change behavior of pulsar and the polarization characteristics under multi-frequency.The pulsar data selected in this thesis is observed by the central beam of 19 beam receiver of FAST.The central frequency is 1250 MHz and the frequency band width is 400 MHz.The average pulse profile and polarization of pulsars are one of the important means to study the characteristics of pulsar.The first study content of this thesis is to select 10 pulsar’s pulse profiles with high signal-to-noise ratio to process and analyze the polarization characteristics.At the same time,the pulse width at 50% and 10% is calculated,and the degree of linear polarization,circular polarization and absolute circular polarization are calculated.Some pulsars selected in this thesis contain interpulse,so the pulse width and polarization parameters of inter-pulse and main-pulse are calculated respectively.In this thesis,it is found that the pulse profiles of two pulsars in the observation results by FAST exist new information that has not been found before,and the polarization evolution characteristics of other pulsars also have different results from the published research results.The multi-frequency characteristic of pulsar is also one of the important means to study pulsars.The second study content of this thesis is to select pulsars with new pulse components to analyze the multi-frequency polarization characteristics.It is found that the bridge radiation and inter-pulse of pulse profile show different evolution results with frequency.Therefore,it is considered that the components of bridge radiation on both sides of the main-pulse of pulsar may have different radiation mechanisms,and it is considered that the bridge radiation is related to the inter-pulse of the radiation mechanisms.The mode change characteristics of pulsars are one of the unsolved problems.The third study content of this thesis is to analyze the polarization characteristics of different modes of PSR J0826+2637.It is found that there are two different modes in the data selected in this thesis,namely strong mode and weak mode,and the radiation intensity in weak mode is 42% of that in strong mode.This thesis also analyzes the polarization characteristics and null characteristics of the two modes.It is considered that the mode change behavior of PSR J0826+2637 is the result of the change of the main-pulse.After separating and processing the single-pulse data,it is found that there is 2.7% of null component.