Igor V. Moskalenko Igor V. Moskalenko (Stanford U.)(Stanford U.)
with
A.Strong (MPE), S.Digel (SLAC), T.Porter (USCS), O.Reimer (SU)
Modeling of the Galactic diffuseModeling of the Galactic diffuse
continuum continuum γγ-ray emission-ray emission
Igor V. Moskalenko 2 July 4, 2006 6th INTEGRAL Workshop/Moscow
GLAST Large Area Telescope (LAT)
EGRET(>100 MeV)
Simulated LAT (>1 GeV, 1 yr)
This is an animation that steps from 1. EGRET (>100 MeV), to 2. LAT (>100 MeV), to 3. LAT (>1 GeV)
Seth Digel
Igor V. Moskalenko 3 July 4, 2006 6th INTEGRAL Workshop/Moscow
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 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
Igor V. Moskalenko 4 July 4, 2006 6th INTEGRAL Workshop/Moscow
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
Igor V. Moskalenko 5 July 4, 2006 6th INTEGRAL Workshop/Moscow
A Model of CR Propagation in the Galaxy
Gas distribution (Leiden-Argentina-Bonn HI, CfA CO surv.)Gas distribution (Leiden-Argentina-Bonn HI, CfA CO surv.)
Interstellar radiation field (87 stellar classes, gas, dust, Interstellar radiation field (87 stellar classes, gas, dust,
including heating and re-emission)including heating and re-emission)
Source distribution (SNR, pulsars)Source distribution (SNR, pulsars)
Nuclear & particle production cross sections (LANL, Nuclear & particle production cross sections (LANL,
Webber)Webber)
Gamma-ray production: brems, IC, Gamma-ray production: brems, IC, ππ00
Energy losses: ionization, Coulomb, brems, IC, synchEnergy losses: ionization, Coulomb, brems, IC, synch
Solve transport equations for all CR species (~90!)Solve transport equations for all CR species (~90!)
Fix propagation parametersFix propagation parameters
Igor V. Moskalenko 6 July 4, 2006 6th INTEGRAL Workshop/Moscow
Wherever you look, the GeV -ray excess is there !
4a-f
EGRET data
Igor V. Moskalenko 7 July 4, 2006 6th INTEGRAL Workshop/Moscow
Reacceleration Model vs. Plain Reacceleration Model vs. Plain DiffusionDiffusion
Plain Diffusion
(Dxx~β-3 R0.6)
DiffusiveReacceleration
B/C ratio
Antiproton flux
Antiproton flux
B/C ratio
Igor V. Moskalenko 8 July 4, 2006 6th INTEGRAL Workshop/Moscow
More excesses: Positron Excess ?
HEAT (Beatty et al. 2004)
GALPROP
GALPROP
1E, GeV
10
e+/e e+/e
HEAT 2000 HEAT 1994-95
HEAT combined
1E, GeV
10
Q: Are all the excesses connected?Q: Are all the excesses connected?
A: “Yes” and “No”A: “Yes” and “No”
Same progenitor (CR p or DM) for pbars, e+’s, γ’s… or a local positron source?
Systematic errors of different detectors
E > 6 GeV
Igor V. Moskalenko 9 July 4, 2006 6th INTEGRAL Workshop/Moscow
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 antiprotonsantiprotons 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
Igor V. Moskalenko 10 July 4, 2006 6th INTEGRAL Workshop/Moscow
Secondary e± are seen in γ-rays !
Improves an agreement in MeV range
brems
IC
In the heliosphere: In the heliosphere: ee++/e~0.2/e~0.2
In the Galaxy: eIn the Galaxy: e++/e~1 <1 /e~1 <1 GeVGeV
electronselectrons
positronspositrons
sec.
Igor V. Moskalenko 11 July 4, 2006 6th INTEGRAL Workshop/Moscow
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
Igor V. Moskalenko 12 July 4, 2006 6th INTEGRAL Workshop/Moscow
Seth Digel’05
Gas Rings: HI (Our Neighborhood)
Longitude
Lati
tud
e
Igor V. Moskalenko 13 July 4, 2006 6th INTEGRAL Workshop/Moscow
Interstellar radiation field
R= 0 kpc4 kpc8 kpc
12 kpc 16 kpc
Local ISRF
stars
IR CMB
The ISRF plays an important role:•Generation of Galactic diffuse -ray emission (IC)•IC energy losses of electrons and positrons
It is very intense in the Galactic center•Attenuation of TeV -ray sources (see Poster 18C !)
scattered
Igor V. Moskalenko 14 July 4, 2006 6th INTEGRAL Workshop/Moscow
Anisotropic Inverse Compton Scattering
Electrons in the halo see anisotropic radiation Observer sees mostly head-on collisions
e-
e-
head-on:large boost &more collisions
γγ
small boost &less collisions
γ
sun
Energy density
Z, kpc
R=4 kpc
Important @ high
latitudes !
Igor V. Moskalenko 15 July 4, 2006 6th INTEGRAL Workshop/Moscow
Effect of anisotropic ICS
Galactic latitude, degrees
Ratio anisoIC/isoIC
Intermediate latitudesGC
anti-GCpole
• The anisotropic IC scattering plays important role in modeling the Galactic diffuse emission
• Affects estimates of isotropic extragalactic background
Igor V. Moskalenko 16 July 4, 2006 6th INTEGRAL Workshop/Moscow
Latitude profile of the outer Galaxy
anisotropic IC
• The aniso IC is maximal (x2) in the outer Galaxy around b=20 -30
• Agreement with data impossible without aniso IC
Latitude
isoIC
bremsstrahlung
0
TotalEG
Igor V. Moskalenko 17 July 4, 2006 6th INTEGRAL Workshop/Moscow
Diffuse emission from the inner Galaxy
• The “optimized” model describes the spectrum of the diffuse emission from MeV to TeV energies
• Predictions down to keV’s (note, INTEGRAL data include positronium continnum)
• MeV region appears to be transitional between Galactic and EG emission dominance
Extragalactic
EGRETASCAHEAO A2HEAO A4
COMPTEL
G+EG EGRET
G COMPTEL(Strong’99)
EG COMPTEL(Weidenspointner’00)
EG EGRET(Strong’04)
INTEGRAL(Strong’05)
isoICanisoIC
Tota
l Gala
ctic
Tota
l Gala
ctic
G+EG
G+EG COMPTEL
Positronium+ sources??
Igor V. Moskalenko 18 July 4, 2006 6th INTEGRAL Workshop/Moscow
Conclusions
• We are building a model of the diffuse emission preparing for the GLAST mission
• The diffuse emission model becomes more realistic now with more prediction capability outside the MeV-GeV region
• MeV region is transitional (Galactic vs. extragalactic dominance)
• On the other hand, GLAST will resolve 1000’s of unresolved sources putting stricter constraints on the diffuse emission model
• Prepare to see unexpected !• This will have an impact on CR studies, derivation
and interpretation of the extragalactic background, and will possibly affect the dark matter studies
Igor V. Moskalenko 19 July 4, 2006 6th INTEGRAL Workshop/Moscow
Diffuse emission from the outer Galaxy
anisotropic IC
isoIC
bremss
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