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Systematic Astro Statistics

Systematic Astro Statistics. Vinay Kashyap CHASC. Hyunsook Lee, Jeremy Drake, Pete Ratzlaff, David van Dyk, Rima Izem, Xiao-li Meng, Taeyoung Park, Aneta Siemiginowska, Alanna Connors, Andreas Zezas. CHASC. CHASC AstroStatistics Collaboration. c.1997

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Systematic Astro Statistics

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  1. Systematic Astro Statistics Vinay Kashyap CHASC Hyunsook Lee, Jeremy Drake, Pete Ratzlaff, David van Dyk, Rima Izem, Xiao-li Meng, Taeyoung Park, Aneta Siemiginowska, Alanna Connors, Andreas Zezas

  2. CHASC CHASC AstroStatistics Collaboration c.1997 Chandra X-ray Center and Harvard University AstroStatistics Collaboration Chandra AstroStatistics Cabal * California-Harvard AstroStatistics Collaboration * Members of the University are expected to take individual responsibility for their participation in any outside activity, and use their best efforts to avoid false or misleading suggestions by others that the activity is an undertaking of Harvard or any of its units. In general, all members should observe the University’s policy on the use of the Harvard name, and limit their identification with Harvard to listing their formal titles as appropriate. CHASC is not an official entity recognized by Harvard University (HU). HU does not endorse any program listed herein. Reference to any product, process, publication, service, or offering of any third party by trade name, trademark, Manufacturer or otherwise does not necessarily constitute or imply the endorsement or recommendation of such by HU. HU is not responsible for representations made here, and does not explicitly or implicitly endorse the views presented herein. And so on and so forth, and so on and …

  3. CHASC high-energy, low-counts, Poisson workshops, papers, codes, weblog

  4. CHASC webpage: http://hea-www.harvard.edu/AstroStat/ The AstroStat Slog: http://groundtruth.info/AstroStat/slog/

  5. AstroStat Slog visibility: Apr 10 - Apr 30, 2008

  6. Project: Incorporate Systematic Error In X-ray Data Analysis The three most important effects that affect data analysis Calibration! Calibration! Calibration!

  7. X-ray analysis: from model to data van Dyk et al. 2001, ApJ, 548, 224

  8. from there to here (E,p,t) : photon energy, location, arrival time (E’,p’) : detector channel, chip location S : astrophysical source model R : energy redistribution function (RMF) P : position redistribution function (PSF) A : effective area (ARF) M : predicted model counts

  9. uncertainty in effective area Drake, Ratzlaff, et al. (2005)

  10. uncertainty in energy response

  11. effect on model parameter uncertainty Probability density 

  12. but how exactly?

  13. MCMC

  14. DATA CALIBRATION Draw parameters Compute likelihood Update parameters

  15. DATA CALIBRATION Draw effective areas Draw parameters Compute likelihood Update parameters

  16. but where do the effective areas come from?

  17. Principal Components

  18. eigenvector eigenvalue ~N (0,1) new nominal bias PCs residual A = A0 + bias + components + residual

  19. what have we got so far? • realistic error bars • implemented in BLoCXS • Sherpa • 100x drop in storage • 500x speed up in analysis • generalize to any instrument • extendable to model lacunae • roll your own

  20. what’s next? unified file format for ingestion into XSPEC/Sherpa other schemes of dimensionality reduction RMFs: 2D PCA, within and between PCA PSFs: multiscale residuals

  21. effect on parameter uncertainty

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