Study On The Linear Polarization Of Pulsars

Pulsars are often considered as strong magnetic neutron stars with high-speed rotation characteristics.There is an angle between the pulsar’s rotation axis and the magnetic axis.When the pulsar’s radiation beam rotates once and can sweep across the earth,a pulse can be received.The measurement of polarization of pulsar is one of the basic topics of pulsar observation research.Pulsar polarization includes linear polarization and circular polarization.Pulsars generally have polarization phenomena,and the polarization profiles of different pulsars or the same pulsar at different observation frequencies are also quite different.Some pulsar linear polarization position angles show a smooth S-shaped curve with longitude,and some pulsars have 90 ° jumps in some positions.Observing the polarization characteristics of pulsars requires high sensitivity of radio telescopes.As a result of the improvement of telescope performance,more and more pulsars with high SNR polarization observation data have been obtained.In this paper,the properties of the linear polarization of pulsars are statistically studied,365 pulsars are selected,which contain 704 polarization profiles with different observation frequencies.Among them,85 pulsars have polarization data with high signalto-noise ratio in three or more observation frequency bands,and are used to study the linear polarization of pulsars with frequency.This paper statistically studies the relationship between pulsar linear polarization and polarization position angle jump,the relationship between linear polarization and the reversal of circular polarization,the difference between the linear polarization characteristics of millisecond pulsars and ordinary pulsars,and so on.The main results obtained from the research in this paper are as follows:(1)The percentage of linear polarization of most pulsars is between 10% and 50%.Rarely,the percentage of linear polarization is less than 10% or greater than 90%.(2)Approximately 30% of the pulsar’s integrated profile will appear depolarized,and the possibility of depolarization once is the largest,and basically no more than 4 depolarizations occur.(3)The polarization position angle jump will appear in part of the integrated profile,of which nearly half is the polarization position angle 90 ° jump.The integrated profile is most likely to appear once or twice,with almost no occurrences of 4 or more.(4)Nearly half of the pulsar’s integrated profile will show a circular polarization sign,of which one or two occurrences are most likely.(5)The degree of linear polarization of pulsars changes with the observation frequency.The possibility that the percentage of linear polarization decreases with the increase of the observation frequency is greater than the possibility that the percentage of linear polarization increases with the increase of the observation frequency.At observation frequencies greater than 1GHz,the polarization intensity of most pulsars appears to decrease as the observation frequency increases.(6)There is a correlation between the polarization position angle jump and depolarization in phase,and the greater the observation frequency,the stronger the correlation.The polarization position angle 90° jump is more likely to correlate with depolarization,and the higher the observation frequency,the stronger the correlation.(7)There is a phase correlation between the polarization position angle jump and the reversal of circular polarization,but the probability of correlation is less than 40%,and the correlation at high frequencies is stronger than that at low frequencies.The polarization position angle 90°jump has a greater correlation with the reversal of circular polarization.(8)It is unlikely that the angular jump,depolarization,and the reversal of circular polarization of the pulsar’s integrated polarization profile will be related at the same time,and it is not related to the observation frequency.But if the polarization position angle is a 90 ° jump,the correlation is enhanced.(9)The average polarization profile of a millisecond pulsar is more complex than a normal pulsar.(10)The linear polarization of a millisecond pulsar is basically the same as a normal pulsar in other properties.