The Research On The Prompt And Multi-band Afterglow Emission Of GRB 181110A

Gamma-ray burst(GRB),the most energetic electromagnetic explode in the universe,contains a prompt emission and long-lasting afterglow emission.Depending on its duration,GRB can be classified as short gamma-ray burst(sGRB)or long gamma-ray burst(1GRB).Accepted by most people,the fireball model interprets the prompt emission as the emission of the internal shocks inside the jet,while the afterglow emission is produced due to synchrotron radiation of electrons in the external shocks as the jet is decelerated by the circumburst medium.The multi-band afterglow data of GRBs can be used to constrain the physical properties of the fireball(e.g.the jet structure and opening angle)and the circumburst medium.Taking the peak time of the early afterglow light curve as the deceleration time,one can estimate the initial Lorentz factor of the fireball.In Chapter 1,a brief introduction of GRB is given,including the history of GRB observations,the prompt emission and afterglow emission,the progenitor of long and short GRBs,fireball model,central engine and other theories.An introduction of the methods to constrain the Lorentz factor of GRBs and the correlations others found in GRBs is also given.In Chapter 2,we perform a comprehensive analysis on the prompt emission and the afterglow data of GRB 181110A,where a clear peak is detected by Swift UVOT and XRT in optical to X-ray bands.With prompt emission spectral analysis we derive that EP=52.87±37.28 keV and Eγ,iso=(13.43±3.49)×1052 erg.Hard-to-soft and intensity-tracking spectral evolution are found in the the spectrum of GRB 181110A.We fit the afterglow data of UVOT and XRT with a smoothly broken power law model and derive the rising(decaying)slopes and the peak time tp=1193-11+12s.We build the spectral energy distribution at about 1400 s after the trigger and find that the SED is well fitted with a single power-law(β=0.99-0.03+0.02).We also fit the late time afterglow of GRB 181110A with afterglowpy.Three structures for the jet’s energy profile are considered:the Top-Hat,the Gaussian,and the Power Law jets.With the slopes we derive and the closure relations of standard afterglow model,we infer the circumburst medium of GRB 181110A is consistent with the ISM case.Besides,the fitting results indicate a uniform jet rather than a structured jet for GRB 181110A.Using the parameters given by afterglowpy,we estimate the typical frequencies of electrons and find vm～1012 Hz and vc～1019 Hz,Which is consistent with our analysis before(vm<v<vc),thus the early peak of the afterglow of GRB 181110A is not produced by frequency crossing.Considering tp>T90,we can calculate the initial Lorentz factor in the thin shell case,where tdec=tp.The initial Lorentz factor of GRB 181110A is derived to be Γ0=169-40+92.We also investigate GRB 181110A in a statistical context and find it is consistent with the Amati relation,though with a large error of Ep,z.Compared with the correlations found by Enwei Liang et al.,we find GRB 181110A locates within the sample of LGRBs with well afterglow onset features.At the end,a conclusion and prospects for the observation in the future are given.