A general method for analysis of extended sources

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A general method for analysis of extended sources

• Larry Wai Ping Wang
• March 2, 2006

2
expert resources used

• Jim Chiang
• Seth Digel
• Igor Moskalenko
• Olaf Reimer
• Andy Strong

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Overview of Talk

1. Software tools
2. Small extended sources
3. Large extended sources

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Basic element FITS map cube

• 3-D objects axes are latitude, longitude, energy
• Background and signal sources for Monte Carlo
  simulation
• Background and signal models for likelihood
  analysis

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Ingredients for analysis of extended objects

• Source models
• GALPROP (galactic diffuse emission simulation)
  output is GALPROP format mapcubes
• Tool for converting GALPROP format mapcube to
  GLAST science tools format mapcube
• Your own tool for making correctly formatted
  mapcubes for the source under study
• GLAST science tools
• gtobssim input is mapcube, output is event data
• gtcntsmap input is event data, output is data
  mapcube
• gtsrcmaps input is source model mapcube, output
  is IRF convolved source model mapcube
• gtlikelihood inputs are data/model mapcubes
• Other software for automation / inspection
• control scripts for automated analysis pipeline
  I use python
• Graphics I use hippodraw http//www.slac.stanfo
  rd.edu/grp/ek/hippodraw/

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Overview of Talk

1. Software tools
2. Small extended sources
3. Large extended sources

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Test case for extended source

• Context of test case simulation of Milky Way
  dark matter satellites (Taylor and Babul
  2004,2005)
• Coordinate of test case
• l,b9.8deg,-31.0deg
• Most of gamma flux is within 1.5 deg of clump
  center
• 70 counts signal, 43 counts background for 55
  days of GLAST (not DC2), within 1.5 deg of clump
  center, Egt1GeV

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Angular distribution(Egt1GeV)
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Energy spectrum(within /- 1.5 deg of clump
center)
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Overview of Talk

1. Software tools
2. Small extended sources
3. Large extended sources

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Test case galactic diffuse analysis

• Likelihood fit for mapcube normalizations from
• GALPROP cosmic ray induced p0
• GALPROP cosmic ray inverse compton
• GALPROP bremsstrahlung
• residual charged particle background
• Isotropic diffuse
• Point sources from catalog group
• Scan through GALPROP cosmic ray models, find best
  fit model(s)

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Analysis of residual charged particle background

• significant mainly in the range below 100 MeV
• large part of it is 'irreducible, i.e. real
  gamma rays
• Julie has posted the DC2 charged particle data
  here https//confluence.slac.stanford.edu/display
  /DC2/backgndDC2-GR-v7r3p5
• Ideas for analyzing residual charged particle
  background
• make map cubes of the residual charged particle
  background
• compare the estimate of residual charged
  particle background with variations in the DC2
  data
• Time-dependent analysis background on vs
  off comparison
• Geomagnetic latitude range comparisons
• zenith angle range comparisons

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test run example

• GALPROP configuration
• Gamma energy range 10 MeV 1TeV
• nucleus injection indices 1.5/2.42 (break
  rigidity 10e3MV)
• electron injection indices 1.5/2.42 (break
  rigidity 20e3MV)
• Observation simulation
• 1-day in-orbit, DC1A IRF
• GALPROP cosmic ray induced p0
• GALPROP cosmic ray inverse compton
• Isotropic extragalactic
• Likelihood model fit
• Energy range 30MeV-200GeV, all sky
• GALPROP cosmic ray induced p0 (free
  normalization)
• GALPROP cosmic ray inverse compton (free
  normalization)
• Isotropic extragalactic (free normalization)

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Example all sky test rundata vs best fit models
GALPROP Cosmic ray IC p0
GALPROP Cosmic ray IC
extragalactic
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Things to do for DC2 analysis

• Include residual charged particle background
• Include found point sources from catalog group in
  DC2 likelihood fit
• Diffuse analysis group should produce a best
  fit model, give diffuse model to catalog group
  for 2nd iteration on source detection?