High-energy Radiative Properties Of Millisecond Pulsars

Since the launch of Fermi Gamma-ray Space Telescope in 2008,about 110 mil-lisecond pulsars(MSPs)have been detected to emit gamma-rays,and then the MSPs are important gamma-ray sources in the Universe.Compared to normal pulsars,the MSPs belong to a subclass of pulsars with weak surface magnetic fields(~10~7-10¹¹G)and old ages(~10~9-10¹⁰years).Both particle acceleration and radiation mechanisms in such these objects are still main topics of concern,studying them is very important for us to further understand pulsar physics.In this thesis,the high-energy radiative proper-ties of MSPs are studied based on the multi-band observed data,and main results are as follows.The high energy emission properties of the MSPs with aligned phases are inves-tigated.For the MSPs with phase-aligned in radio and?-ray bands,it is assumed that the pulsar magnetosphere ia approximated by the dipole magnetic field with a current-induced magnetic field.To obtain the best-fitting model parameters,gamma-ray light curves of three MSPs(PSR J0034-0534,PSR J1939+2134,and PSR J1959+2048)cal-culated in the outer gap(OG)and two pole caustic(TPC)models are simulated by using the Markov Chain Monte Carlo(MCMC)technique.Our results show that(1)both TPC and OG models can rebuild?-ray light curves of these three MSPs well;(2)MSPs emit high energy photons with smaller inclination angles(??10°-50°),larger view angles(??65°-100°),and smaller perturbation factor((?)?-0.15--0.1);and(3)the factor(?),describing the strength of the perturbed magnetic field,is all less than zero in these two models,so the magnetic field caused by current-induced play a leading role in the pulsed location of MSPs.The high-energy pulsed radiation of MSPs are studied in the striped wind(SW)model.In the SW model,gamma-rays are produced in the regions outside the light cylinder.Here the original SW model is revised,i.e.,both acceleration and radiation of relativistic electrons are located in finite regions of the striped winds outside the light cylinder,and these electrons in the finite regions satisfy the distribution of a power law with an exponential cut-off.In the revised SW model,gamma-ray light curves and phased-averaged spectra for three kinds of MSPs are calculated,where pulsed?-rays are produced by the inverse Compton scattering of the relativistic electrons with cosmic microwave background.The MCMC method is used to look for best fits of inclination angle and view angle,which are two important model parameters after other model parameters are constrained.Our calculating results can reproduce the observed light curves and phase-average spectra of PSR J0030+0451,PSR J1939+2134,and PSR J1744-1134 well.Pulsed?-ray properties and statistical properties of 22 MSPs with double peaks are studied in the revised version of the OG and SW models.The major differences between these two models are magnetic field structures,?-ray production sites,and ra-diation mechanisms.Our results indicate that(1)both models can reproduce observed double-peak structures of the MSPs well,(2)for most MSPs,a relatively large magnetic inclination angle(?~50°-90°)and small viewing angle(?~30°-90°)are obtained in the OG model,but a relatively small??[20°,60°]and large??[70°,150°]in the SW model.Statistical analysis for the MSPs further show that the spin-down power posi-tively correlates with the cut-off energy of phase-averaged spectra and?-ray luminosity,which is consistent with observed those by Fermi-LAT.Therefore,it may be concluded that the OG and the SW models for describing high-energy emissions of MSPs can not be ruled out at present,and further studies are required.