cosmic ray propagation models and interpretation of results from recent space experiments
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Cosmic ray propagation models and interpretation
of results from recent space experiments
Fiorenza Donato Department of Theoretical Physics, Un. Torino
Marcel Grossman Meeting – Session AP3 Paris, july 17, 2009
Crs production and propagation historyCharged nuclei - isotopes - antinuclei
Moskalenko, Strong & Reimer astro-ph/0402243
1. Synthesis and acceleration
* Are SNR the accelerators? * How are SNR distributed? * What is the abundance at sources? * Are there exotic sources out of the disc?
2. Transport in the Milky Way
* Diffusion by galactict B inhom.
* Interaction with the ISM: - destruction - spallation production of secondaries
* electromagnetic losses - ionization on neutral ISM - Coulomb on ionized plasma
* Convection
* Reacceleration
3. Solar Modulation
* Force field approximation? * Charge-dependent models?
Acceleration of GCRs: SNRs
SNR RX J0852.0-4622 Observed in X-ray & -rays
(Hess Coll. A&A 2005)
If all from hadronic sources IS acceleration spectrum
BUT: how much is IC?
(E) E- =2.10.1
Predictions of supernova shock acceleration: (E) E- = 2.0-2.1 (Berezhko & Ellison 1999, Baring et al. 1998)
Complex SNR CTB 37 Observed in X-ray & -rays
(Hess Coll. arXiv:0803.0702)
Hadron dominated scenariomore likely
Determination of acceleration spectrum
Ellison, Patnaude, Slane, Blasi, Gabici ApJ 2007
Gabici & Aharonian ApJL 2007
Proton induced -rays- from SNR (top)
- from a cloud at 100 pc from SNR (1,2,3,4: different explosion times)
IC and -decay Emission
20 MeV – 300 GeV explorable by GLASTshould allow a discrimination between
hadronic and leptonic emissions
Transport equation in diffusion models
DiffusionConvection Destruction on ISM
CR sources: primaries, secondaries (spallations)
Reacceleration
Ionization, Coulomb, Adiabatic,Reacceleration
Characteristic times for various processes
The smaller the time, the most effective the process is
For protons:escape dominates > 1 GeV
For E<1 GeV, convection and e.m. losses. For iron:
Spallations dominate for E<10 GeV/n
Spatial origin of primary CRs
Taillet & Maurin A&A 2003
Diffusive modelsJopikii & Parker 1970; Ptuskin & Ginzburg, 1976; Ginzburg, Khazan & Ptuskin 1980; Weber, Lee & Gupta 1992, ....
Some recently developped diffusive models:
1. Maurin, FD, Taillet, Salati ApJ 2001; Maurin, Taillet, FD A&A 20022. Strong & Moskalenko ApJ 1998; Moskalenko, Strong, Ormes, Potgieter, ApJ 2002 3. Shibata, Hareyama, Nakazawa, Saito ApJ 2004; 20064. Jones, Lukasiak, Ptuskin, Webber ApJ 2001 (Modified Weighted-slab technique)5. Evoli, Gaggero, Grasso, Maccione JCAP 2008 (only at HE)
Ingredients:
- Geometry of the galaxy- Distribution of the sources- Acceleration spectrum- Distribution and composition of ISM - Diffusion coefficient- Electromagnetic energy losses- Destruction cross sections- Production cross sections- Radioactive isotopes- Convection- Reacceleration- ........
IF and HOW these elements
are includedshapes the model
2-zone Semi-analytic Diffusive ModelMaurin, FD, Taillet, Salati ApJ 2001; Maurin, Taillet, FD A&A 2002
• Diffusion coefficient K(R)=K0R
• Convective velocity Vc
• Alfven velocity VA
• Diffusive halo thickness L• Acceleration spectrum Q(E)=p
K0, , Vc, VA, L, ()
+All the effects included (VA0 & VC0)
+2D semi-analytic
+ Local Bubble for radioactives
- ISM constant
-VC constant througout the halo
- VA in the disk
Systematic scan of parameter space
Evaluation of uncertainties
Results on Observed Prim/SecMaurin, FD, Taillet, Salati, ApJ (2001) Maurin, Taillet, FD A&A (2002)
Systematic scan of the parameter space6 free parameters: diffusion (K0,), convection (VC),
acceleration(α), reacceleration (VA), diffusive halo (L)
Only model WITH convection AND reacceleration
Kolmogorov (δ=0.3) spectrum disfavoured, δ ~ 0.6-0.7, K0 ~ 0.003-0.1 kpc2/Myr
Acceleration spectrum α~2.0
No need for breaks in K(E) or Q(E)
Diffusive model in Galprop Strong & Moskalenko ApJ 1998; Moskalenko, Strong, Ormes, Potgieter, ApJ
2002
+ All the effects included
+ Full 3D – numerical approach
+ Distribution of gas and sources
Diff+Conv=0.60 (0 if R<4GV)
=2.46/2.16
Diff+Reacc =0.33, =0.43
Qualitative (not quantitative) fits
Breaks in spectra and K(E)
Convection + reacceleration: not best fit
Results on protons and antiprotons
Conventional (solid) Optimized (dots)
Models tuned forGamma rays
But new FERMI data…
Strong, Moskalenko, Reimer ApJ 2004
More results on radioactives,absolute fluxes,
electronsand positron, ....
Results from Jones et al. ApJ 2001
Modified weighted slab technique applied to different models Fits to secondary/primary
Simplified modelsNo reacceleration + convectionGood fit to B/C (C, Fe)High diffusion power spectraHigh accel. spectra (2.35-2.40)Break (at non-rel. E, reacc. only)
Results from Shibata, Hareyama, Nakazawa, Saito, APJ 2004; 2006
Fully 3D analytical model with reacceleration and losses (no ion.), no boundaries, simple exponential forms for distributions, no
convection
Qualitative agreement with data
No definite propagation model comes out
High degeneracy of models
Need more data around 1 GeV/n and at >20-30 GeV/n
What consequences on antimatter fluxes?
Antiprotons data
Demodulated data cover ~ 0.7 ÷40 GeV All experiments from ballons (residual atmosphere) except AMS98
Pamela preliminary data: compatible with these secondaries
Secondary CR production
FD, Maurin, Brun, Delahaye, Salati PRL 2009
Antiproton/proton: data and models
Small uncertainties – excellent fit to data – consistencyNO need for new phenomena (astrophysics/particle
physics)
Donato et al. PRL 2009
Predictions with the same semi-analytical DM as for positrons(and B/C, radioactive isotopes)
PROTON flux:Φ=Aβ-P1R-P2
•T<20 GeV: Bess 1997-2002(Shikaze et al. Astropart. Phys. 2007)
•T>20 GeV, our fit (Bess98, BessTeV&AMS): {24132; 0; 2.84}
More astrophysical clues with antiprotons
Re-acceleration in mature SNRs –
High energy preliminary Pamela data do not show increasing flux
Blasi & Serpico arxiv:0904.0871
Allowed Enhancement factors for DARK MATTERcontribution in antiproton data
Limits obtained for:
• <σv>=3·10-26 cm3/s
• MED prop parameters
• Cored Isoth DM
• ρ=0.3 GeV/cm3
• 2σ error bars, T>10 GeV
Limits get weaker for increasing masses
Boost < 6-20-40 for m=0.1-0.5-1 TeV
Enhancement of the antiproton flux?
• Clumpiness in the DM distribution in the Milky Way: energy
dependent (Lavalle, Yaun, Maurin, Bi A&A 2008)
boost factors may be different for positrons, antiprotons, gamma
rays, … (Lavalle, Pochon, Salati, Taillet A&A 2006)
a low boost factor (for gamma rays) emerges from most recent N-
body simulations (Diemand et al. 2008; Springel et. MNRAS 2008; Brun, Delahaye, Diemand, Profumo, Salati 0904.0812)
• Enhancement of the annihilation cross section (Bergstrom PLB 1989; Hisano et al. PRL 2004)
depends on the mass (> TeV)
Compatibility with positron data?
Propagation of secondary positronsDelahaye, Lavalle, Lineros, FD, Fornengo, Salati, Taillet A&A 2009
Diffusive semi-analytical model: Thin disk and confinement halo Free parameters fixed by B/C
Above few GeV: only spatial diffusion and energy losses
Energetic positrons are quite local
Positron flux: data and predictions
Same propagation models as for B/C (Maurin, FD, Salati, Taillet ApJ 2001)
Positron flux well described by secondary contribution
Uncertainties due to propagation
Positron/electron: data and predictionsDelahaye et al. A&A 2009
Yellow band: secondary positrons & propagation uncertainties
Hard electrons: γ=3.34
There is no “standard” flux – dashed is B/C best fit
Stro
ngly d
isfav
oure
d by
Ferm
i and
pre
lim. P
amela
FERMI Electrons and PAMELA positron fraction
Models adjusted on Fermi e-, breaks at 4 GeV (acceleration)No Klein-Nishina losses
FERMI Electrons and PAMELA positron fraction:contribution from local pulsars (d<3 kpc) (Grasso et. Al 0905.0636)
Excellent description of both e- and e+/(e+e-)
Conclusions and perspectives
• Diffusive models with reacceleration/convection reproduce data for many species without too many adjustements
• A definite model does not come out – degeneracies and uncertainties
• Antimatter in CRs and particle DM in the galaxy: strong connection! Mostly limited by propagation uncertainties, astrophysical backgrounds,
data
• Data from different species: nuclei, isotopes (rad., K), electrons and positrons, antiprotons, gamma-rays, on a large energetic range, are needed
• Many crucial experimental breakthroughs are just around the corner!
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