X-ray Observational Studies Of The Supernova Remnant Cassiopeia A And The Black Hole Candidate MAXI J1535-571

By using observational data from the high-resolution,high-sensitivity and wide energy band X-ray satellites,we have investigated the X-ray emission properties of supernova remnants and the temporal properties of black hole X-ray binaries.The first work in this thesis was mainly conducted to investigate the X-ray emission properties of the supernova remnant Cassiopeia A(Cas A)using observational data from the Chandra.The fluxes of sulfur and silicon in the SE and NW regions of the remnant and the distribution dependence of their flux ratios with the radius of the remnant are obtained from the generated energy spectra for subregions of the supernova remnant Cas A and their corresponding energy spectra fitting parameters.It is found that the flux ratios of sulfur and silicon are increasing with the increased remnant radius,indicating that the explosive ejecta outside the remnant is heated by the reverse shock wave in advance.In addition,the peak values of sulfur and silicon flux ratios in the SE and NW regions appear at different radii,which may be caused by the asymmetric outburst of the predecessor star of Cas A.We have also found that the centre energy of iron lines in both regions increase with the remnant radius,which can be attributed to the different duration of the reverse shock wave,resulting in different ionization states of iron ions.Interestingly,the centre energy of iron lines in the SE and NW regions are well correlated,indicating that lump expansions in SE and NW regions are essentially synchronized.The second work in this thesis was primarily to demonstrate the the temporal phenomena of the black hole X-ray binary MAXI J1535-571 during its outburst in2017 using observations from the first Chinese X-ray astronomical satellite,the Insight-HXMT.It is found that when the source is in different burst states,the types of power density spectrum are significantly different.Obvious band-limited noise and quasi-periodic oscillation components can be detected in the hard intermediate state.Further analysis show that the characteristic frequency of low-frequency band-limited noise is positively correlated with the energy,that is,the characteristic frequency of soft energy photons is less than that of the hard ones.The RMS spectra of band-limited noise in the frequency range of 0.1-0.5Hz show average peak values in both the hard and soft intermediate states,while there are differences at the high energy tail.This phenomenon is on account of the different proportion of energy spectrum components that dominant noise RMS spectra.Although the C-type QPO RMS spectrum maintains similar trend when the spectral states transition from hard intermediate state to soft one,a state-dependent phenomenon can be clearly seen in the band-limited noise RMS spectrum.