Study On The Gravitational Effects And Eclipses Mechanisms Of Binary Pulsar PSR J1748-2446

Pulsars are special sources of coherent radiation in the universe.Their radiation properties,strong magnetic field and high speed rotation make them one of the hot topics in astrophysics.So far,the development of pulsar observation has promoted many researches in astrophysics,such as the radiation mechanism of pulsars,the properties of the interstellar medium,the detection of gravitational waves,the internal structure of neutron stars,the dynamics of globular clusters,and the theory of relativistic gravity.Pulsar binaries are systems consisting of a pulsar and its companion stars orbiting each other.According to general relativity,if a pulsar’s spin direction is different from the normal plane of its orbit,the pulsar will precession.The strong gravitational properties of binary pulsar can indirectly prove the existence of gravitational waves,and they are the cosmic laboratory to test the predictions of general relativity.The occultation of binary pulsar systems has always been a hot topic in the radio observation and theoretical research of pulsars.The observation and study of occultation will be helpful to understand the occultation mechanism and the properties of pulsar wind and radiation mechanism,as well as to better study the dynamics,evolution and interstellar medium of binary pulsar stars.Occultation binary stars may also provide information about the evolution history of isolated millisecond pulsars,the interstellar medium and magnetic field between pulsars and companion stars,and other important phenomena,so the study of occultation phenomenon of binary stars is of great significance.Several possible models have been developed to explain the mechanism of occultation,such as refraction,free-free absorption,inverse Compton scattering,cyclotron and synchrotron absorption,However,the best masking mechanism model has not been obtained.Because the types of companion stars,magnetic field intensity,radiation characteristics and other properties of different pulsed binary systems are very different,different occultation systems tend to have different occultation mechanisms.Therefore,it is necessary to verify the masking mechanism with our observational data.The millisecond binary pulsar system PSR J1748-2446 A in the globular cluster Terz5 was observed using the Parkes64 m radio telescope in Australia.It is the second pulsar occultation binary system discovered.We observed it at 1400 MHz for almost a year.The occultation of the pings was observed at nearly a third of the orbital phase.We use the time-measuring properties of this pulsar to verify the properties of general relativity.The occultation model of PSR J1748-2446 A is verified by the relationship between the optical depth during occultation,the density of electron column,the temperature of the occulting medium plasma,the scattering Angle and other parameters.The main results obtained in this paper are as follows:(1)By studying the pulse arrival time of the system,it is found that the observed attenuation of the orbital period of the pulsar is basically consistent with the theoretical attenuation predicted by general relativity.(2)By analyzing pulsar pulse arrival time,the dispersion measure,electron density and optical depth generated by interstellar medium are calculated.(3)By fitting the electron density and optical depth during the occultation,it is found that the free-free absorption model can well explain the dependence between the duration of occultation and the observation frequency,although the ambient temperature required by the model is much lower.(4)By fitting the relationship between electron density and optical depth during masking under the inverse Compton scattering model,it is found that the scattering Angle is too large and does not conform to the actual range.(5)In cyclotron absorption,the magnetic field required under the lower harmonics is much higher than the magnetic field near the companion star,and the calculated occultation temperature under the harmonics is much higher than the temperature limited by the model.(6)The required flow rate calculated under the synchronous absorption model is greater than the flow rate measured by the system.Therefore,to sum up,the masking mechanism of the system cannot be explained by a single model,but may be the result of the combined action of multiple mechanisms.