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Update on the Intermediate-Scale Structure

Update on the Intermediate-Scale Structure. Gary Walker Los Alamos National Laboratory. Introduction. Significance Map: No g/h cut, 5.1 ° bin. Significance Map: A4 weighted analysis, Gaussian smoothing. Intermediate-scale structure seen in map with no gamma/hadron cut

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Update on the Intermediate-Scale Structure

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  1. Update on the Intermediate-Scale Structure Gary Walker Los Alamos National Laboratory

  2. Introduction Significance Map: No g/h cut, 5.1° bin Significance Map: A4 weighted analysis, Gaussian smoothing • Intermediate-scale structure seen in map with no gamma/hadron cut • Also visible in x2, A4 maps

  3. Seasonal Effect? • Split data into seasons • Same structure seen in all of them

  4. Brian’s Anisotropy • Simulations indicate that Brian’s anisotropy will cause a mis-estimation of the background • However, this does not seem to be the cause of the structures at RA≈70° and ra≈130°

  5. Declination Slice 10° < Dec < 20°, 1° Binning in RA (Independent 10° x 1° Bins) Full Dataset (Total Int Duration = 2150 days) Red = Sky Red = Sky Black = Bkg Black = Bkg • Region at ra=70° does not appear to be an underestimation of the background

  6. Compare with Tibet Anisotropy • Similarity seen with Tibet anisotropy ( > 4TeV, 1997-2005), especially at ra=70°

  7. What is it? • Brightest spot (around ra=70°) in no g/h cut map: Excess = 165 K, Bkg = 220 M • S/B = (7.5 ± 0.7) x 10-4 • Brightest spot (around ra=70°)in A4>1 map: Excess = 34.4 K, Bkg = 19.7 M • S/B = (17.5 ± 2.5) x 10-4 This is inconsistent by 3.8σ • A4 for a steep spectrum gamma source will look like background • A4 for a hard spectrum proton source will look more gamma-like

  8. nTop > 150 Cut nFit > 20, No Gamma/Hadron Cut nTop > 150, No Gamma/Hadron Cut • Bottom map has 20% of the number of events in the top map • Based only on statistics, significance should drop to ~4.5σ

  9. Summary / What to do next? • The features at ra≈70° and ra≈135° appear to be real • Suggestions for further tests? • Brian’s anisotropy doesn’t appear to be the cause, but may be causing some mis-estimation of the background – use simulation to correct • Use gamma and proton simulations to quantify what kind of spectrum will produce the observed A4 and nTop behavior • Any other suggestions?

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