The High-Energy Data Integration Analysis Tool And The Research Of Gravitational Lensing Effect And Physics In Gamma-Ray Bursts

Various high-energy astrophysical sources in the universe serve as natural laboratories for studying extreme physics,and high-energy gamma-ray detection is one of the important research methods.Due to the fact that the Earth’s atmosphere absorbs most high-energy gamma photons,space-based gamma-ray detection is necessary.Gammaray space telescopes originated from the monitoring of nuclear tests during the Cold War,during which gamma-ray bursts(GRBs)were accidentally discovered.The study of such burst phenomena has now become a frontier of science worldwide.Currently,international gamma-ray telescopes in operation include the Fermi and Swi f t satellites,while domestically,the "Wukong" gamma-ray telescope and the "Huairou-1" GRB allsky monitor have been launched.The Purple Mountain Observatory and other units are also proposing the development of the next-generation flagship facility,the Very Large Area gamma-ray Space Telescope(VLAST),which will work in the ultra-wide energy range of MeV-TeV.To fully utilize multi-wavelength observational data from existing facilities and comprehensively reveal the physical origins of GRBs and their afterglows,as well as prepare for the research applications of future facilities such as VLAST,we have developed the High-Energy Detection data Integration Analysis Tool(HEt ool s).This highly modular tool has been successfully applied in a series of studies and can be easily extended to new high-energy detection facilities such as VLAST.This thesis mainly introduces the basic framework of HEtools and its application in GRB data analysis.For the latter,we take lensed GRBs as the entry point and expand to the relevant physics of GRBs.Chapter 1 of the thesis introduces the basic knowledge of GRBs and gravitational lensing and the development status of related research.Considering that the Very Large Area Gamma-ray Space Telescope project is relatively new,and it is also one of the main service objects of HEtools developed by us in the future,so we give a brief introduction to the VLAST project,describe the basic framework of HEt ool s,and briefly summarize some applications that have been carried out so far in Chapter 2.Chapter 3 of the thesis mainly introduces the application and extension of our HEtools in the study of lensed GRBs.We combined the detection data from multiple space-based high-energy gamma-ray monitors(Swift-BAT,Fermi-GBM,HXMTHE/CsI),searched for possible lensed GRB candidates through the autocorrelation function of the light curve,and verified the candidates using the Bayesian inference method of the lensed light curve model.In addition,we also considered the characteristics of the empirical relation(Ep,z-Eγ,iso)and the test of different pulse hardness ratios.We found that GRB 200716C is a possible lensed short GRB,and the redshift mass of the foreground object can be obtained through time delay and magnification factor,which is(1+zl)Ml=4.25-1.36+2.46×105M⊙(90%confidence range).This could serve as evidence for the existence of intermediate-mass black holes.We have also carried out power density spectrum analysis on the GRBs observed by Fermi-GBM,looking for possible periodic signals.Among them,it is found that there may be repeated light curve behaviors in GRB 201104A.We try to explain it in the context of lensing and propose a Bayesian inference method for lensed spectral models.This method can naturally consider the variation of the instrument background and response function,which will plays an important role in identifying lensed GRBs in different events.Chapter 4 of the thesis introduces the application of Daily brefing system in the HEtools.By checking the daily analysis briefing,we found that the energy spectrum parameters of GRB 220426A are quite special,its low energy spectrum index is very hard,while its high energy spectrum index is very soft.After further analysis,we verified that GRB 220426A is a very rare GRB dominated by thermal components through the Bayesian inference of the energy spectrum.We calculated the evolution of the bulk Lorentz factor Γ and the photosphere radius Rph via the thermal component in the time-resolved spectrum,and compare with the empirical relations(Γ-L,Ep-L).The results show that GRB 220426A and GRB 090902B are very similar,and they both consistent with this two relations very well.Our results verify again that this two empirical relations can be explained under the photosphere radiation model,and provide a new evidence for the photosphere emission in GRBs.Chapter 5 of the thesis mainly introduces the work of using high-energy photons of GRBs to measure(constrain)the intergalactic magnetic field.We analyzed GRB 221009A,the brightest GRB observed in human history,and found the gamma photon with the highest energy(～400 GeV)observed in Fermi-LAT so far.Assuming that the photon comes from the cascade radiation of TeV photons,then we can calculate the intergalactic magnetic field strength(BIGMF～4 ×10-17 G)through the delay time and energy of the photon.We also use ELMAG to conduct a Monte Carlo simulation of the cascade radiation under the intergalactic magnetic field,and combine the simulation results with observations to further exclude the smaller magnetic field strength(BIGMF～10-17-10-18 G).Furthermore,we extended this analysis pipeline on HEtools and searched the Fermi-LAT GRBs catalog for possible secondary highenergy photons.Although the current results cannot provide new constraints on the strength of the intergalactic magnetic field,this method will continue to be applied to future observational data.The last chapter of the thesis summarizes the above work,expounds the continuous expansion and improvement process of HEtools,and looks forward to the arrival of the next generation of instruments and the future research direction.