1. Igor V. Moskalenko (Stanford) with S. Digel (SLAC) T. Porter (UCSC) O. Reimer (Stanford) O. Reimer (Stanford) A. W. Strong (MPE) A. W. Strong (MPE) Diffuse Galactic  -ray emission model

2. Igor V. Moskalenko 2 March 2, 2006DC2/SLAC GLAST LAT Project Diffuse Galactic Gamma-ray Emission ~80% of total Milky Way luminosity at HE !!! Tracer of CR (p, e − ) interactions in the ISM (π 0,IC,bremss): oStudy of CR species in distant locations (spectra & intensities)  CR acceleration (SNRs, pulsars etc.) and propagation oEmission from local clouds → local CR spectra  CR variations, Solar modulation oMay contain signatures of exotic physics (dark matter etc.)  Cosmology, SUSY, hints for accelerator experiments oBackground for point sources (positions, low latitude sources…) Besides: o“Diffuse” emission from other normal galaxies (M31, LMC, SMC)  Cosmic rays in other galaxies ! oForeground in studies of the extragalactic diffuse emission oExtragalactic diffuse emission (blazars ?) may contain signatures of exotic physics (dark matter, BH evaporation etc.) Calculation requires knowledge of CR (p,e) spectra in the entire Galaxy

3. Igor V. Moskalenko 3 March 2, 2006DC2/SLAC GLAST LAT Project Conventional model vs EGRET data 4a-f Conventional model consistent with local p,e spectra exhibits the “GeV excess:” a factor ~2  0 IC Bremss EG We must have at least 2 diffuse emission models with/without the excess

4. Igor V. Moskalenko 4 March 2, 2006DC2/SLAC GLAST LAT Project galprop ID = 6002029RB Based on Strong,Moskalenko,Reimer, 2004, ApJ 613,962 Strong,Moskalenko,Reimer,Digel,Diehl, 2004, A&A 422, L47  Optimized to fit EGRET data (GeV excess: CR spectra)  Includes secondary electrons & positrons  Pulsar/SNR source distribution  Gradient in X-factor (H 2 /CO) Improvements:  new HI, CO data (Digel)  new interstellar radiation field (Porter)  fine adjustments to reflect these new inputs Examples of model unconvolved and convolved with EGRET PSF DC2 diffuse emission model

5. Igor V. Moskalenko 5 March 2, 2006DC2/SLAC GLAST LAT Project GeV excess: Optimized/Reaccleration model Uses all sky and antiprotons & gammas to fix the nucleon and electron spectra  Uses antiprotons to fix the intensity of CR nucleons @ HE  Uses gammas to adjust  the nucleon spectrum at LE  the intensity of the CR electrons (uses also synchrotron index)  Uses EGRET data up to 100 GeV protons electrons x4 x1.8 antiprotons E k, GeV pbars e + -flux γ-rays Strong etal 2004

6. Igor V. Moskalenko 6 March 2, 2006DC2/SLAC GLAST LAT Project Secondary e ± are seen in γ-rays ! Lots of new effects ! Improves an agreement at LE brems IC Heliosphere: e + /e~0.2 electrons positrons sec.

7. Igor V. Moskalenko 7 March 2, 2006DC2/SLAC GLAST LAT Project

8. Igor V. Moskalenko 8 March 2, 2006DC2/SLAC GLAST LAT Project Distribution of interstellar gas Neutral interstellar medium – most of the interstellar gas mass –21-cm H I & 2.6-mm CO (standing for H 2 ) Differential rotation of the Milky Way – plus random motions, streaming, and internal velocity dispersions – is largely responsible for the spectrum This is the best – but far from perfect – distance measure available Self-absorption of HI (21cm) and optical depth effects… Dame et al. (1987) Hartmann & Burton (1997) (25°, 0°) W. Keel CO H I G.C. 25°

9. Igor V. Moskalenko 9 March 2, 2006DC2/SLAC GLAST LAT Project New H2 maps (S.Digel)

10. Igor V. Moskalenko 10 March 2, 2006DC2/SLAC GLAST LAT Project New HI maps (S.Digel)

11. Igor V. Moskalenko 11 March 2, 2006DC2/SLAC GLAST LAT Project Interstellar Radiation Field Systematic errors:  Star distribution –star counts  Grain properties –lab measurements  Gas/dust proportion –extinction curve  “Reasonable parameters”  Compare with ISRF data only at R  Target for CR leptons (IC) Energy losses Model components:  Geometrical: disk, ring, halo, bar, triaxial bulge, arms  87 stellar types (main sequence), AGB & exotics  Dust: silicate, graphite, PAH (5Å – few  m)  Absorbed light gives mid-IR (small grains +PAH) and FIR (~0.1-1  m grains) SMR00 PS05 Old model Local ISRF (PS05) R=0 Optical Scatt.opt. IR PAH 4 kpc 12 kpc 16kpc

12. Igor V. Moskalenko 12 March 2, 2006DC2/SLAC GLAST LAT Project Distribution of CR Sources & Gradient in the CO/H 2 CR distribution from diffuse gammas (Strong & Mattox 1996) SNR distribution (Case & Bhattacharya 1998) sun X CO =N(H 2 )/W CO : Histo –This work, Strong et al.’04 ------Sodroski et al.’95,’97 1.9x10 20 -Strong & Mattox’96 ~Z -1 – Boselli et al.’02 ~Z -2.5 - Israel’97,’00, [O/H]=0.04,0.07 dex/kpc Pulsar distribution Lorimer 2004

13. Igor V. Moskalenko 13 March 2, 2006DC2/SLAC GLAST LAT Project Inner Galaxy region Comparison with EGRET & COMPTEL spectral data Other regions demonstrate equally good agreement

14. Igor V. Moskalenko 14 March 2, 2006DC2/SLAC GLAST LAT Project Convolution with EGRET PSF:  Important below 1 GeV  A large effect at low energies especially in latitude affecting the overall spectral shape  Convolution itself is model dependent - depends on spectrum, not fully accounted for Model comparison with data

15. Igor V. Moskalenko 15 March 2, 2006DC2/SLAC GLAST LAT Project UnconvolvedConvolved Longitude profile |b|<5  Effect of Convolution: 70-100 MeV

16. Igor V. Moskalenko 16 March 2, 2006DC2/SLAC GLAST LAT Project UnconvolvedConvolved Latitude profile |l|<30  Effect of Convolution: 70-100 MeV

17. Igor V. Moskalenko 17 March 2, 2006DC2/SLAC GLAST LAT Project UnconvolvedConvolved Longitude profile |b|<5  Effect of Convolution: 0.5-1 GeV

18. Igor V. Moskalenko 18 March 2, 2006DC2/SLAC GLAST LAT Project UnconvolvedConvolved Latitude profile |l|<30  Effect of Convolution: 0.5-1 GeV

19. Igor V. Moskalenko 19 March 2, 2006DC2/SLAC GLAST LAT Project 1000 – 2000 MeV 1-2 GeV Convolution effect is negligible

20. Igor V. Moskalenko 20 March 2, 2006DC2/SLAC GLAST LAT Project NB here the spatial convolution correction is applied to the DATA based on the model. Hence the DATA changes, not the model (procedure appropriate for spectra) “Convolved data”De-convolved Effect of De-Convolution: Spectrum |l|<30  |b|<5 