Exercise 5: Use All You Know About GRB 090510

You have now successfully fit the GBM data for GRB 090510 using standard models. The Fermi GBM and LAT teams' spectral analysis of this burst is here:

arXiv:1005.2141 which is published as Ackermann, M. et al. 2010, ApJ, v716, p1178.

How would you go about trying to find the extra component in the GBM data alone?

Go back to your time-integrated fit for GRB 090510, using your original set of detectors. Redo your best model fit.

You can see that the fit to the BGO data is not so good with the Band function, particularly at high energies.

Try adding a power-law component but holding down the <CTRL> key and adding model 1 to model 5.

You will likely need to set your initial parameters carefully. Use the 'Set Parameters' box in the Photon Model widget to bring up the box that shows the starting values.

If you need, press 'Default' to reset the parameters to reasonable default values before entering your new guesses.

Try adding a power-law component to model 7 instead of model 5, again experimenting with your starting parameters for the power-law component.

What does this exercise tell you about the spectrum of this burst and the ability to measure it using GBM data alone?

You can experiment with individual time bins, too.

To see more about the detection of extra components in GBM data alone, please look at the following paper:

arXiv:1009.5045 which will soon appear as Sylvain Guiriec et al. in ApJ.

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