sep-04

EGRET and the local EGRET and the local interstellar emissioninterstellar emissionEGRET and the local EGRET and the local interstellar emissioninterstellar emission

Isabelle Grenier & Jean-Marc Casandjian

Service d’Astrophysique, CEA Saclay

sep-04

the local interstellar the local interstellar emissionemission

the local interstellar the local interstellar emissionemission

EGRET, 9 years, 0.5°x0.5° local medium: 5° ≤ |b| ≤ 80°

sep-04

the local interstellar the local interstellar modelmodel

the local interstellar the local interstellar modelmodel

iipred

iiprediobs

2CRCRHI

2H2

bkgsouICIC)VB(dust)CO(2H)HI(HI

N)Nln(NLln

)H(n)HI(n ifq2

q

)CO(W

)H(NX

TSAIII~

qE~

qW~

qN~

qN

iipred

iiprediobs

2CRCRHI

2H2

bkgsouICIC)VB(dust)CO(2H)HI(HI

N)Nln(NLln

)H(n)HI(n ifq2

q

)CO(W

)H(NX

TSAIII~

qE~

qW~

qN~

qN

sep-04

ISM mapsISM mapsISM mapsISM 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)

oexpN~

ISM

sep-04

interstellar fit without interstellar fit without IC emissionIC emission

interstellar fit without interstellar fit without IC emissionIC emission

both models with ISMHI+CO and ISMEGRET badly need IC emission

2ln(L) increase by ~ 15000 and ~19000 !

ISMHI+CO

ISMEGRET

sep-04

interstellar fit without interstellar fit without IC emissionIC emission

interstellar fit without interstellar fit without IC emissionIC emission

NHI+WCO >> ISMEGRET because Xlocal ~ 1.0 ± 0.1 < XGal ~ 1.56 ± 0.05

warm dust total dust

HI+CO+EBV

HI+CO+I100

HI+CO

ISMEGRET+EBV

EBV

ISMEGRET

I100

830

180 1 02

0

270290

19 870

14 5

302 ln

(L)

sep-04

interstellar fit with interstellar fit with dustdust

interstellar fit with interstellar fit with dustdust

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?

sep-04

3EG sources3EG sources3EG sources3EG sources

|b|< 5°

|b|> 5°

sep-04

exposure and albedo exposure and albedo problemsproblems

exposure and albedo exposure and albedo problemsproblems

best model residuals

albedo contamination?

high- exposure

problem?

sep-04

exposure and albedo exposure and albedo problemsproblems

exposure and albedo exposure and albedo problemsproblems

fraction of exposure

at high inclination

with high albedo flux

sep-04

on-going activitieson-going activitieson-going activitieson-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