EGRET and the local interstellar emission Isabelle Grenier

EGRET and the local interstellar emission Isabelle Grenier & Jean-Marc Casandjian Service d’Astrophysique, CEA Saclay sep-04

the local interstellar emission v EGRET, 9 years, 0. 5°x 0. 5° v local medium: 5° ≤ |b| ≤ 80° sep-04

the local interstellar model sep-04

ISM maps • • sep-04 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)

interstellar fit without IC emission v both models with ISMHI+CO and ISMEGRET badly need IC emission v 2 ln(L) increase by ~ 15000 and ~19000 ! ISMHI+CO ISMEGRET sep-04

interstellar fit without IC emission v NHI+WCO >> ISMEGRET because Xlocal ~ 1. 0 ± 0. 1 < XGal ~ 1. 56 ± 0. 05 v warm dust v total dust 10 18 830 20 HI+CO+I 100 HI+CO+EBV 0 2 ln(L) HI+CO I 100 19 870 14 53 0 290 ISMEGRET sep-04 270 ISMEGRET+EBV

interstellar fit with dust v v v sep-04 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?

3 EG sources |b|> 5° |b|< 5° sep-04

exposure and albedo problems v best model residuals albedo contamination? high- exposure problem? sep-04

exposure and albedo problems v fraction of exposure at high inclination v with high albedo flux sep-04

on-going activities v implementation of Heal. Pix maps • equal area bins even near poles • factor of ~2 fewer bins careful with flux conservation ! v and likelihood analysis • fast convolution (nested) • PSF in spherical harmonics v update EGRET source list off the plane v compute the IC emission from the local dust mm ISRF sep-04