GLEAM for DMWG

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GLEAM for DMWG

• Eduardo do Couto e Silva
• Oct 23 , 2002
• SLAC

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Main objective

• Develop a likelihood program to search for
  photons from neutralino annihilations using the
  new GLEAM Monte Carlo.
• This work leverages on the development of the
  data analysis infrastructure for LAT IT
  maintained by Xin Chen, who was kind enough to
  provide us with his nuggets of wisdom

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Shopping list

• Source flux for different MSSM models (e.g
  DarkSUSY). See A. Morsellis talk.
• Background flux (e.g EGRET parametrization used
  in Bergstrom et al Astr. Phys 9 (1998), 137.)
• Orbit model for GLAST See T. Burnetts talk.
• Energy resolution See CAL group report in LAT
  IDT meeting
• PSF See W. Atwoods report in LAT IDT meeting
• Likelihood program

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The approach

• Develop a simple likelihood program and
  interfaces the main ingredients described in the
  previous page
• Develop software infrastructure for systematic
  studies
• Implement a more sophisticated likelihood
  approach to maximize our sensitivity based on
  details of the LAT design.

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Signal and Background
Likelihood of event i to be a neutralino signal
we assume s b . Es
Likelihood of event i to be a background
(To be replaced by measured spectrum from GLEAM
with including orbital effects and appropriate
normalizations from DarkSUSY)
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Extended Likelihood
Fit parameters Nbg number of expected
background events Ns number of expected
photons a power law coefficient Es
neutralino energy
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a 2.2 2.4 2.6 2.7
Nb 1156 554 269 188
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An example of Fitted Parameters
Input value 60
Input value 50
Input value 1156
Input value 2.2
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LAT sensitivity
Each point corresponds to 1000 MC experiments And
assumes a 5 sigma detection threshold
D
E/E
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Summary

• We have developed a simple likelihood code and
  some infrastructure to run GLEAM
• We have started to run GLEAM with the orbit
  corrections (not presented in this talk)
• We are eager to work with the v3 release of GLEAM