Investigating The Scintillation Phenomenon Of Pulsars In Globular Clusters

Pulsars are rapidly rotating neutron stars that emit lighthouse-like beams of radiation at the magnetic poles.The observation of pulsars is mainly influenced by the radiation mechanism of pulsars and the propagation effect of pulsar signals in the interstellar medium.Among them,the observation characteristics caused by the intrinsic changes of pulsar radiation mechanism mainly include the sub-pulse drift,nulling and mode changing of pulsars.The observed phenomena caused by the propagation of interstellar medium mainly include dispersion,Faraday rotation and interstellar scintillation.We tried to study the scintillation of pulsars observationally.Firstly,we review the research progress of pulsar diffraction scintillation and introduce the mechanism of pulsar interstellar scintillation.This paper briefly describes the research methods of diffraction scintillation and summarizes the progress of diffraction scintillation observation in recent years.The research progress mainly includes the use of scintillation effect to limit the fluctuation spectrum of electron density in the interstellar medium,the estimation of tangential velocity of pulsars,the resolution of the scale of pulsar radio radiation region,the acquisition of binary orbit parameters of pulsars,and the search for non-pulsed radio radiation of pulsars.The research work on pulsar scintillation observation by some mainstream radio telescopes is summarized.Second,we report observations of four pulsars in globular clusters using the Parkes and FAST telescopes,respectively.The scintillation patterns were analyzed,and by fitting the two-bit autocorrelation functions of the dynamic spectra of PSRs J0024-7204 C,B1516+02A and B1639+06A,we obtained their characteristic time and frequency and calculated their scintillationvelocity.We first detected the scintillation arcs in the secondary spectra of PSRs B1516+02A,B1639+06A and B2127+02A,respectively.This is also the first time to detect the scintillation arcs of pulsars in globular clusters.By fitting the curvature of the scintillation arc,we obtained the positions of the scattering screens that caused the scintillation of the three pulsars,which were 4.93± 1.36 kpc,1.63± 0.33 kpc and 3.8± 3.2kpc from the earth respectively.The uncertainty of the scintillation screen distance mainly came from the uncertainty of the scintillation arc boundary.This paper introduces the scintillation observation results of Parkes telescope and FAST telescope,and predicts the prospect of the study of pulsed scintillation by FAST telescope.