Modified from talk of Modified from talk of

Igor V. Moskalenko (Stanford U.)Igor V. Moskalenko (Stanford U.)

GALPROP GALPROP

&&

Modeling the Diffuse Modeling the Diffuse -ray -ray

Emission Emission

CR Interactions in the Interstellar Medium

e+-

PPHeHe

CNOCNO

X,γ

gas

gas

ISRF

e+-

π+-

PP__

LiBeBLiBeB

ISM

diffusiondiffusion energy losses energy losses reaccelerationreacceleration convectionconvection etc.etc.

π0

synchrotron

IC

bremss

Chandra

GLAST

ACEhelio-modulation

pp

42 sigma (2003+2004 data)

HESS Preliminary

SNR RX J1713-3946SNR RX J1713-3946

PSF

B

HeHeCNOCNO Fl

ux

20 GeV/n

CR species: Only 1 location modulation

e+-

π+-

PAMELABESS

AMS

Diffuse Galactic Gamma-ray Diffuse Galactic Gamma-ray EmissionEmission

~80% of total Milky Way luminosity at HE !!!

Tracer of CR (p, e−) interactions in the ISM (π0,IC,bremss):o Study of CR species in distant locations (spectra & intensities)

CR acceleration (SNRs, pulsars etc.) and propagationo Emission from local clouds → local CR spectra

CR variations, Solar modulationo May contain signatures of exotic physics (dark matter etc.)

Cosmology, SUSY, hints for accelerator experimentso Background for point sources (positions, low latitude sources…)

Besides:o “Diffuse” emission from other normal galaxies (M31, LMC,

SMC) Cosmic rays in other galaxies !

o Foreground in studies of the extragalactic diffuse emissiono Extragalactic 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

Transport Equations ~90 (no. of CR species)

ψψ((rr,p,t),p,t) – – density per total momentum

df

Vpdt

dp

p

ppppDp

p

Vxx

D

prqt

tpr

3

1

22

][

),(),,(

sources (SNR, nuclear reactions…)sources (SNR, nuclear reactions…)

convection convection (Galactic wind)

diffusiondiffusion

diffusive diffusive reacceleration reacceleration

(diffusion in the momentum space)

E-lossE-loss

fragmentationfragmentation radioactive decayradioactive decay

+ boundary conditions

CR Propagation: Milky Way Galaxy

Halo

Gas, sources

100

pc 40 kpc

4-12

kpc

0.1-0.01/ccm

1-100/ccm

Intergalactic space

1 kpc ~ 3x1018 cm

R Band image of NGC8911.4 GHz continuum (NVSS), 1,2,…64 mJy/ beam

Optical image: Cheng et al. 1992, Brinkman et al. 1993Radio contours: Condon et al. 1998 AJ 115, 1693

NGC891

Sun

“Flat halo” model (Ginzburg & Ptuskin 1976)

What it takes to model CR propagation in the Galaxy

Gas distribution (energy losses, Gas distribution (energy losses, ππ00, brems), brems)

Interstellar radiation field (IC, eInterstellar radiation field (IC, e±± energy losses) energy losses)

Nuclear & particle production cross sectionsNuclear & particle production cross sections

Gamma-ray production: brems, IC, Gamma-ray production: brems, IC, ππ00

Energy losses: ionization, Coulomb, brems, IC, synchEnergy losses: ionization, Coulomb, brems, IC, synch

Assume propagation model (Dxx, Dp, Va)Assume propagation model (Dxx, Dp, Va)

Source distribution & injection spectraSource distribution & injection spectra

Solve transport equations for all CR speciesSolve transport equations for all CR species

Fix propagation parametersFix propagation parameters

More Effects: Local Environment

Sun

Regular Galactic magnetic fieldmay establish preferentialdirections of CR propagation

Sun

GC

~200pc

Local Bubble:A hole in the interstellar gas is formed in a series of SN explosions; some shocks may still exist there…May be important for radioactive CR species, but Dxx=?

CR Source Distribution

SNR source

The CR source (SNRs, pulsars) distribution is too narrow to match the CR distribution in the Galaxy assuming XCO=N(H2)/WCO=const (CO is a tracer of H2)

Lorimer 2004

PulsarsCR afterpropagation

diffuse γ-raydistribution

Distribution of CR Sources & Gradient in the CO/H2

CR distribution from diffuse gammas (Strong & Mattox 1996)

SNR distribution (Case &Bhattacharya 1998)

sun

XXCOCO=N(H=N(H22)/W)/WCOCO::

Histo –This work, Strong et al.’04----- -Sodroski et al.’95,’971.9x1020 -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

Electron Fluctuations/SNR stochastic events

GeV electrons 100 TeV electronsGALPROP/Credit S.Swordy

Energy losses

107 yr

106 yr

Bremsstrahlung

1 TeV

Ionization

Coulomb

IC, synchrotron

1 GeV

Ekin, GeV

E(d

E/d

t)-1,y

r

Electron energy loss timescale:

1 TeV: ~300 kyr 100 TeV: ~3 kyr

Wherever you look, the GeV -ray excess is there !

4a-f

EGRET data

Diffuse -ray emission models

0.5-1 GeV

>0.5 GeV

Dark MatterCosmic Ray

Spectral VariationsEGRET “GeV Excess”

There are two possible BUT fundamentally different explanations of the excess, in terms of exotic and traditional physics:

Dark MatterCR spectral variations

Both have their pros & cons.

from Strong et al. ApJ (2004)from de Boer et al. A&A (2005)

from Hunter et al. ApJ (1997)

GeV excess: Optimized/Reaccleration model

Uses Uses all skyall sky and antiprotons & gammas and antiprotons & gammas to fix the nucleon and electron spectrato fix the nucleon and electron spectra

Uses Uses antiproton fluxantiproton flux to fix to fix the the intensityintensity of CR nucleons @ HE of CR nucleons @ HE

Uses Uses gammasgammas to adjust to adjust the nucleon spectrum at LEthe nucleon spectrum at LE the the intensity intensity of the CR electrons of the CR electrons (uses also synchrotron index)(uses also synchrotron index)

Uses EGRET data Uses EGRET data up to 100 GeVup to 100 GeV

protonsprotonselectronselectrons

x4x4

x1.8

antiprotonsantiprotons

EEkk, GeV, GeV

EEkk, GeV, GeV

EEkk, GeV, GeV

Diffuse Gammas at Different Sky RegionsDiffuse Gammas at Different Sky Regions

Intermediate latitudes:l=0°-360°,10°<|b|<20°

Outer Galaxy:l=90°-270°,|b|<10°

Intermediate latitudes:l=0°-360°,20°<|b|<60°

Inner Galaxy:l=330°-30°,|b|<5°

Hunter et al. region:l=300°-60°,|b|<10°

l=40°-100°,|b|<5°

corrected

Milagro

Longitude Profiles |b|<5Longitude Profiles |b|<5°°

50-70 MeV

2-4 GeV

0.5-1 GeV

4-10 GeV

Latitude Profiles: Inner Galaxy

50-70 MeV 2-4 GeV0.5-1 GeV

4-10 GeV 20-50 GeV

Latitude Profiles: Outer Galaxy

50-70 MeV

2-4 GeV

0.5-1 GeV

4-10 GeV

Example “Global Fit:” diffuse Example “Global Fit:” diffuse γγ’s, pbars, ’s, pbars, positrons positrons

Look at the combined (pbar,e+,γ) data Possibility of a successful “global fit”

can not be excluded -non-trivial !

pbars

e+

γ

GALPROP/W. de Boer et al. hep-ph/0309029GALPROP/W. de Boer et al. hep-ph/0309029

Supersymmetry: MSSM (DarkSUSY) Lightest neutralino χ0

mχ ≈ 50-500 GeV S=½ Majorana

particles χ0χ0−> p, pbar, e+, e−,

γ

Pohl et al.2003

sun

Positions of the local clouds

The Excess: Clues from the Local The Excess: Clues from the Local MediumMedium

Digel et al.2001

Observations of the local medium in different directions, e.g. local clouds, will provide a clue to the origin of the excess (assuming it exists). Inconclusive based on EGRET data

Yes No

Poor knowledge of π0-production cross

section: better understanding of π0-production

Dark Matter signal:look for spectral signatures in cosmic rays (PAMELA, BESS, AMS) and in collider experiments (LHC)

Possibility: cosmic-ray spectral variations.Further test: look at more distant clouds

Will GLAST see the excess?

EGRET data