EGRET and the local interstellar emission

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EGRET and the local interstellar emission

• Isabelle Grenier Jean-Marc Casandjian
• Service dAstrophysique, CEA Saclay

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the local interstellar emission

• EGRET, 9 years, 0.5x0.5
• local medium 5 b 80

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the local interstellar model
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ISM maps

• NHI from Hartmann Burton 97 and Dickey
  Lockman 90
• WCO from Dame et al. 01
• dust extinction from Finkbeiner 99 and Schlegel
  98
• IC from GALPROP (Strong Moskalenko)

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interstellar fit without IC emission

• both models with ISMHICO and ISMEGRET badly need
  IC emission
• 2ln(L) increase by 15000 and 19000 !
• ISMHICO
• ISMEGRET

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interstellar fit without IC emission

• NHIWCO gtgt ISMEGRET because Xlocal 1.0 0.1 lt
  XGal 1.56 0.05
• warm dust ?
• total dust ???

2 ln(L)
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interstellar fit with dust

• NHI WCO EBV IC sou Ibkgd very
  preliminary!
  
• Xlocal (1.1 0.1) 1020 mol. cm-2 K-1 km-1 s
• (1.00 0.05) ? sources ? little bias on the IS
  model parameters
• cold gas associated with cold dust?
• or IC emission from FIR dust emission?

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3EG sources
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exposure and albedo problems

• best model residuals
• albedo contamination?
• high-? exposure
• problem?

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exposure and albedo problems

• fraction of exposure
• at high inclination
• with high albedo flux

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on-going activities

• implementation of HealPix maps
• equal area bins even near poles
• factor of 2 fewer bins
• careful with flux conservation !
• and likelihood analysis
• fast convolution (nested)
• PSF in spherical harmonics
• update EGRET source list off the plane
• compute the IC emission from the local dust mm
  ISRF