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EGRET and the local interstellar emission

EGRET and the local interstellar emission. Isabelle Grenier & Jean-Marc Casandjian Service d’Astrophysique, CEA Saclay. the local interstellar emission. EGRET, 9 years, 0.5°x0.5° local medium: 5° ≤ |b| ≤ 80°. the local interstellar model. ISM maps.

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EGRET and the local interstellar emission

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  1. EGRET and the local interstellar emission Isabelle Grenier & Jean-Marc Casandjian Service d’Astrophysique, CEA Saclay

  2. the local interstellar emission • EGRET, 9 years, 0.5°x0.5° • local medium: 5° ≤ |b| ≤ 80°

  3. the local interstellar model

  4. 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)

  5. interstellar fit without IC emission • both models with ISMHI+CO and ISMEGRET badly need IC emission • 2ln(L) increase by ~ 15000 and ~19000 ! ISMHI+CO ISMEGRET

  6. interstellar fit without IC emission HI+CO+EBV 830 HI+CO+I100 1 020 180 HI+CO 270 ISMEGRET+EBV 290 14 530 EBV 19 870 I100 ISMEGRET • NHI+WCO >> ISMEGRET because Xlocal ~ 1.0 ± 0.1 < XGal ~ 1.56 ± 0.05 • warm dust  • total dust  2 ln(L)

  7. interstellar fit with dust • NHI + WCO + EBV + IC + sou + Ibkgd very preliminary! • Xlocal ~ (1.1 ± 0.1) 1020mol. 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?

  8. 3EG sources |b|> 5° |b|< 5°

  9. exposure and albedo problems • best model residuals albedo contamination? high- exposure problem?

  10. exposure and albedo problems • fraction of exposure at high inclination • with high albedo flux

  11. 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

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