Fitting a Spectral Model

Now that we have a response file, we can fit the spectrum using Xspec. In the Command Window, type:

xspec

Enter the data, background, and response file at the prompts, and edit the fitting parameters as needed.

      XSPEC> data P0134520301R1S001SRSPEC1001.FIT ! input data 
      XSPEC> back P0134520301R1S001BGSPEC1001.FIT ! input background
      XSPEC> resp r1_o1_rmf.fits                  ! input response file
      XSPEC> model wabs*mekal                     ! set spectral model to absorbed mekal
      wabs:nH> 0.01             
      mekal:kT> 1    
      mekal:nH>            
      mekal:Anbundanc> .4    
      mekal:Redshift>      
      mekal:Switch> 0    
      mekal:norm> 1    
      XSPEC> renorm
      XSPEC> fit 100
      XSPEC> setplot energy
      XSPEC> setplot command window all
      XSPEC> setplot command log x off
      XSPEC> setplot command wind 1
      XSPEC> setplot command r y 0.01 40
      XSPEC> plot data chisq
      XSPEC> exit

Figure 8.3 shows the fit to the spectrum.

Figure 8.3: 1st order RGS1 spectrum of AB Dor. The fit is an absorbed single-temperature mekal model. The gap between 0.9 - 1.2 keV is due to the absence of CCD7.