Research On The Properties Of The Gamma-ray Burst Jet Driven By A Magnetar And Related X-ray Polarization Detection Technology

Gamma-ray bursts(GRB s)are generated by ultra-relativistic jets in collapse of massive stars or the merger of compact binaries.They are ideal astronomical laboratory for studying the birth of compact objects(neutron stars and black holes),relativistic shock waves,and the star formation and evolution.The discovery of gravitational waves from the merger of compact binaries marks a milestone of the multi-messenger ear in studying on GRB physics.More recently,the polarization measurement expands the study of GRB s from spectrum and light curve to a new dimension of polarization.Guangxi University,together with the Chinese Academy of Sciences and domestic universities,proposed a soft X-ray polarimeter(SXP)project for China space station,aiming to detect the polarization of GRBs with a new type of soft X-ray gas detector.The study of polarization detection technology is the basis of SXP design,and the exploration of GRB jet properties can provide a scientific basis for the feasibility of the SXP observation program.During my program for a master's degree,I fully participated in the scientific research and related detection technology research of SXP project.In the first chapter of this thesis,the scientific research progress of GRB is reviewed.In the second chapter,the international and domestic satellite programs related to GRB observation are briefly introduced,with emphasis on the scientific objectives and development progress of SXP project.The third,fourth and fifth chapters report our research resultsIn Chapter 3,we study the characteristics of the jet driven by a newly-born magnetar.The jet structure of GRB 170817A associated with gravitational wave burst is structured,and its central engine may be a magnetar.The early afterglow of a large number of GRBs observed by Swift satellite has the characteristics of an X-ray plateau,which is generally believed to be caused by the magnetic dipole radiation of anewly-born magnetar.Motivating the observations of GRB170817A,we speculate that the GRB jet and the dipole radiation wind driven by a newly-born magnetar may also be structured,and the difference in luminosity of different GRBs and their early X-ray plateaus may be due to viewing angle effects.If such a quasi-universal j et is parameterized with a uniform-luminosity core surrounding by cocoon whose luminosity decay as a power-law function,our Monte Carlo analysis shows that when the luminosity of the core area is logLc;/erg/s=52.68-0.33+0.76e opening angle of the core ?c,j=2.10°-1.28°+1.90(50%confidence level)and the power-law decay index of the cocoon is kj=4.00-0.37+0.27(1? confidence level),the observed redshift and luminosity distributions can be well reproduced,and the inferred local GRB rate is p0=9.6 Gpc-3yr-1 Similarly,the X-ray luminosity function of the dipole radiation wind can be empirically described by a broken power-law function with the parameter set{?1,?2,logLb,w}={0.78,2.22,48.51}.Under the assumption that the magnetar dipole radiation wind is also collimated and coaxial with the relativistic GRB jet,it is found that the structure of the magnetar dipole radiation wind is similar to that of the GRB jet structure,with logLc,w/ergs-1?48.38(?)-?C,W=2.65°-1.19°+1.73°,kw=4.57-0.75+1.21(1? confidence level).We also present the simulated GRB survey in the soft X-ray band with the Einstein Probe(EP)satellite.In Chapter 4,we study the possible polarization measurement in the soft X-ray band with SXP.Polarization measurement is essential for understanding the central engine,jet structure and radiation physics of GRBs.The scientific goal of the SXP project is to measure the polarization of prompt emission,X-ray flares and early X-ray plateaus of GRBs.We collect the data observed with the Swift satellite since its launch in 2004 and obtain a sample of 76 GRBs with bright X-ray flares and 117 X-ray plateaus.With this sample as an input,we conduct SXP pre-research on the polarization measurement of these bright X-ray radiation.We find that the number of GRB X-ray MDP<10%and MDP<20%is about 2 and 6 GRBs,respectively,without considering the real space operation environment of the detector.The polarization measurement for the X-ray plateaus may be made with MDP<25.5%and may be around 7 per year.These results are helpful for the design optimization of SXP.In Chapter 5,we study one of the key detection techniques of SXP.The polarization measurement with SXP is based on the thick gas electron multiplier(THGEM).We measure the 55Fe X-ray source after the THGEM gas detector is filled with different components and different proportions of working gases to study the gain and energy resolution of THGEM detector under different gas conditions.The gas used includes Ar/CO2,Ar/CF4,Ar/C4H10,Ne/DME,Ne/CF4.The experimental results of THGEM detector under different mixed gases show that under Ar/C4H10(95%/5%)conditions,the gain of THGEM detector can reach 7 ×103.When Ar/C4H10 as the working gas is chosen,the required working voltage of the THGEM detector is low,the gain is high,and the energy resolution is getting better.Based on this,the SXP prototype has obtained high quality electron track.