Transcript Document

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 history
Charged nuclei - isotopes - antinuclei
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
Moskalenko, Strong & Reimer
astro-ph/0402243
3. Solar Modulation
* Force field approximation?
* Charge-dependent models?
Acceleration of GCRs: SNRs
Predictions of supernova shock acceleration: (E)  E-
(Berezhko & Ellison 1999, Baring et al. 1998)
SNR RX J0852.0-4622
 Observed in X-ray & -rays 
(Hess Coll. A&A 2005)
(E)  E- =2.10.1 
If all from hadronic sources
  IS acceleration spectrum
BUT: how much is IC?
Complex SNR CTB 37
Observed in X-ray & -rays
(Hess Coll. arXiv:0803.0702)
Hadron dominated scenario
more likely
 = 2.0-2.1
Determination of acceleration spectrum
Gabici & Aharonian ApJL 2007
IC and -decay Emission
20 MeV – 300 GeV explorable by GLAST
should allow a discrimination between
hadronic and leptonic emissions
Ellison, Patnaude, Slane, Blasi, Gabici ApJ 2007
Proton induced -rays
- from SNR (top)
- from a cloud at 100 pc from SNR
(1,2,3,4: different explosion times)
Transport equation in diffusion models
Diffusion
Convection
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 models
Jopikii & Parker 1970; Ptuskin & Ginzburg, 1976; Ginzburg, Khazan & Ptuskin 1980; Weber, Lee & Gupta 1992, ....
Some recently developped diffusive models:
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Maurin, FD, Taillet, Salati ApJ 2001; Maurin, Taillet, FD A&A 2002
Strong & Moskalenko ApJ 1998; Moskalenko, Strong, Ormes, Potgieter, ApJ 2002
Shibata, Hareyama, Nakazawa, Saito ApJ 2004; 2006
Jones, Lukasiak, Ptuskin, Webber ApJ 2001 (Modified Weighted-slab technique)
Evoli, Gaggero, Grasso, Maccione JCAP 2008 (only at HE)
Ingredients:
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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 included
shapes the model
2-zone Semi-analytic Diffusive Model
Maurin, FD, Taillet, Salati ApJ 2001; Maurin, Taillet, FD A&A 2002
+All the effects included (VA0 & VC0)
+2D semi-analytic
+ Local Bubble for radioactives
- ISM constant
-VC constant througout the halo
- VA in the disk
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Diffusion coefficient K(R)=K0bRd
Convective velocity Vc
Alfven velocity VA
Diffusive halo thickness L
Acceleration spectrum Q(E)=p
K0, d, Vc, VA, L, ()
Systematic scan
of parameter space
Evaluation of uncertainties
Results on Observed Prim/Sec
Maurin, FD, Taillet, Salati, ApJ (2001) Maurin, Taillet, FD A&A (2002)
Systematic scan of the parameter space
6 free parameters: diffusion (K0,d), 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
d=0.60 (0 if R<4GV)
=2.46/2.16
Diff+Reacc
d=0.33, =0.43
Qualitative (not quantitative) fits
Breaks in spectra and K(E)
Convection + reacceleration: not best fit
Results on protons and antiprotons
Strong, Moskalenko, Reimer ApJ 2004
Conventional (solid)
Optimized (dots)
Models tuned for
Gamma rays
But new FERMI data…
More results
on radioactives,
absolute fluxes,
electrons
and positron, ....
Results from
Jones et al. ApJ 2001
Modified weighted slab technique applied to different models
Fits to secondary/primary
Simplified models
No reacceleration + convection
Good fit to B/C (C, Fe)
High diffusion power spectra
High 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
FD, Maurin, Brun, Delahaye, Salati PRL 2009
Secondary CR production
Demodulated data cover ~ 0.7 ÷40 GeV
All experiments from ballons (residual atmosphere) except AMS98
Pamela preliminary data: compatible with these secondaries
Antiproton/proton: data and models
Predictions with the same semi-analytical DM as for positrons
(and B/C, radioactive isotopes)
Donato et al. PRL 2009
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}
Small uncertainties – excellent fit to data – consistency
NO need for new phenomena (astrophysics/particle physics)
More astrophysical clues with antiprotons
Blasi & Serpico arxiv:0904.0871
Re-acceleration in mature SNRs –
High energy preliminary Pamela data do not show increasing flux
Allowed Enhancement factors for DARK MATTER
contribution 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
Boost < 6-20-40 for m=0.1-0.5-1 TeV
Limits get weaker for increasing masses
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 positrons
Delahaye, 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 predictions
Delahaye 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
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
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Diffusive models with reacceleration/convection
reproduce data for many species without too many adjustements
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A definite model does not come out – degeneracies and uncertainties
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Antimatter in CRs and particle DM in the galaxy: strong connection!
Mostly limited by propagation uncertainties, astrophysical backgrounds, data
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Data from different species: nuclei, isotopes (rad., K), electrons and positrons,
antiprotons, gamma-rays, on a large energetic range, are needed
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Many crucial experimental breakthroughs are just around the corner!