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Robust Point Source Detection with Wavelet Technique

Explore a new method for source detection using wavelet technology. This technique provides accurate estimations for point sources. Multiple AGN generations modeled successfully. Get insights on AGN population analysis. Refinement and documentation needed.

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Robust Point Source Detection with Wavelet Technique

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  1. UW “Source Detection” Status Disclaimer: We are not really in the source-detection game: this is not a good method for finding seeds Toby Burnett, for Sean Robinson UW source detection status Sep 29, 2004 - T. Burnett

  2. What we have • New, simple PSF, Aeff parameterization • Multiple point source generator • Input: specified logN/logS distribution • Multichromatic continuous wavelet transform (MCWT) • Projection of a set of photon positions and energies • A peak is an estimator of: • Signal size • Source position • Significance (with separate estimate of total) • One-year AGN study • Use model of Stecker & Salamon for AGN population • Quick MC to generate photons according to PSF. • Estimate number of sources, sensitivity UW source detection status Sep 29, 2004 - T. Burnett

  3. New PSF parameterization Two parameters: : scale factor, corresponds to rms for gaussian : exponent UW source detection status Sep 29, 2004 - T. Burnett

  4. Example fits UW source detection status Sep 29, 2004 - T. Burnett

  5. Multiple point source generator • Behaves like a standard flux source • Input: logN/logS function UW source detection status Sep 29, 2004 - T. Burnett

  6. Multichromatic Continuous Wavelet Transform (MCWT) Continuous Multichromatic UW source detection status Sep 29, 2004 - T. Burnett

  7. Estimators from peak of MCWT • Value: the rate • Position • Significance (from auxiliary measurement of background) UW source detection status Sep 29, 2004 - T. Burnett

  8. Wavelet estimator performance Background to signal ratio The wavelet sigma is ~10% worse than full ML. UW source detection status Sep 29, 2004 - T. Burnett

  9. AGN population model • The inspiration: this plot from Stecker and Salamon. • Data points:EGRET identified and presumed AGN population • Solid line: their model • Dashed line: -3/2 power • GLAST sensitivity: from AO document • Question: is observed high-lattitude diffuse consistent with undetected AGN’s? UW source detection status Sep 29, 2004 - T. Burnett

  10. Ingredients in the calculation • The logN/logS function from S&S, input to the special source generator. • Constant fluxes, with fixed spectral index 2.15. • The instrument model (PSF, Aeff) • Only front section used • One year observation UW source detection status Sep 29, 2004 - T. Burnett

  11. Sean’s result: detect 2673 UW source detection status Sep 29, 2004 - T. Burnett

  12. Conclusions, outlook • This wavelet technique provides robust and accurate estimation of point sources • Multiple AGN generation according to model works fine • Have a preliminary estimate of number of AGNs a 1-year survey would see, and corresponding limit on remaining diffuse • Both tools need refinement, documentation UW source detection status Sep 29, 2004 - T. Burnett

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