GLEAM for DMWG
description
Transcript of 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 I&T 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. Morselli’s talk. Background flux (e.g EGRET parametrization used in Bergstrom et al Astr. Phys 9 (1998), 137.)
Orbit model for GLAST – See T. Burnett’s talk.
Energy resolution – See CAL group report in LAT IDT meeting
PSF – See W. Atwood’s 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
2
2
2
)(
2
1
sEE
s e(i)L
)(iE
a(i)bg L
Likelihood of event i to be a neutralino signal
Likelihood of event i to be a background
we assume . Es
(To be replaced by measured spectrum from GLEAM with including orbital effects and appropriate
normalizations from DarkSUSY)
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N
isbg
ssbgbgN
sbgNN
NN
iNiN
N
NNe sbg
1
)()(
!
LLL
Fit parameters
Nbg = number of expected background events
Ns = number of expected photons
= power law coefficient
Es = neutralino energy
Extended Likelihood
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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 experimentsAnd assumes a 5 sigma detection threshold
E/E
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Summary
We have developed a simple likelihood code and some infrastructure to run GLEAMWe 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