X-ray spectral fitting methods workshop

Workshop audience
  • When: 24-25. September 2019
  • Where: Max Planck Institute for extraterrestrial Physics, Garching, Germany
  • Who: 44 participants. Speakers: Johannes Buchner, J Michael Burgess, Joern Wilms, Jeremy Sanders, Konrad Dennerl

Video recordings, Slides & Links


The full workshop is available on YouTube: Part I Part II Part III.
Use the Youtube description text to jump to specific talks.


  • wilms_linear.pdf: X-ray astronomy basics: motivation, mirrors & detectors, (linear) data model, ARF&RMF, pile-up, forward-folding.
  • buchner.pdf: Welcome, basic count statistics, Cash/Chi², Backgrounds, Likelihoods, Bayes theorem, Parameter space exploration algorithms (local and global optimizers, MCMC, nested sampling), best fit distributions, posterior distributions, model comparison methods, simulations for calibrating decisions, low-count spectra, practical pointers
  • wilms_minimization.pdf: Understanding Levenberg-Marquardt Minimization.
  • burgess.pdf: Backgrounds (from fits, gaussian, poisson, per-bin), Significance/signal-to-noise ratios, multi-wavelength fits, likelihood ratios, Wilks' theorem, component detection, chi² & degrees of freedom, posterior predictive checks, residuals, stacking data vs information, hierarchical models.
  • wilms_optimal_binning.pdf: Optimal binning of RMFs (Kaastra & Bleeker, 2016, A&A 587, A151)
  • sanders.pdf: X-ray spectral fitting in 2D
  • dennerl.pdf: Calibration uncertainties, Randomization, PHA to PI

Links & Papers


We thank:
  • Surangkhana Rukdee for taking videos and photos
  • Frau Rochner (MPE) for organising seminar room & coffee breaks
  • Maria Depner (MPE) for helping find guest accomodation
  • Birgit Boller (MPE) for helping organising
  • Kirpal Nandra (MPE) for patronage
  • Herr Burghardt (MPE) for video recording equipment
  • The participants for interesting discussions!
Main presenters: Joern Wilms, Johannes Buchner, J Michael Burgess (left to right)