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La stima dei flussi di raggi cosmici di origine secondaria

La stima dei flussi di raggi cosmici di origine secondaria. Fiorenza Donato Dipartimento di Fisica Teorica & INFN, Torino MAPS – Methods of Analysis for Physics in Space Perugia, October 23, 2009. « A theory of the origin of cosmic radiation is proposed

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La stima dei flussi di raggi cosmici di origine secondaria

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  1. La stima dei flussi di raggi cosmici di origine secondaria Fiorenza Donato Dipartimento di Fisica Teorica & INFN, Torino MAPS – Methods of Analysis for Physics in Space Perugia, October 23, 2009

  2. «A theory of the origin of cosmic radiation is proposed according to which cosmic rays are originated and accelerated primarly in the interstellar space of the galaxy by collisions against moving magnetic fields. One of the features of the theory is that it yields naturally an inverse power law for the spectral distribution of cosmic rays […]. » Enrico FERMI, PRD 75 (1949) 1169

  3. GALACTIC COSMIC RAYS (GCRs) • are charged particles diffusing in the • galactic magnetic field • Observed at Earth with • E~ 10 MeV/n – 103 TeV/n • SOURCES • PRIMARIES: • directly produced in their sources • SECONDARIES: • produced by spallation reactions of primaries • on the interstellar medium (ISM) • 2. ACCELERATION • SNR are considered the powerhouses for CRs • They can accelerate particles up to 102 TeV • 3. PROPAGATION • CRs are diffused in the Galaxy by the inhomogeneities of the galactic magnetic field. • During propagation they interact with the ISM (spallation) and loose/gain energy with different mechanisms Charged GCRs: nuclei & isotopes antinuclei leptons Neutral GCRs: gamma rays neutrinos Gaisser astro-ph/0608553

  4. Primaries = present in sources: Nuclei: H, He, CNO, Fe; e-, (e+) in SNR (pulsars) e+, p+, d+ from Dark Matter annihilation Secondaries = NOT present in sources, thus produced by spallation of primary CRs (p, He, C, O, Fe) on ISM Nuclei: LiBeB, sub-Fe; e+, p+, d+; …

  5. Crs production and propagation historyCharged nuclei - isotopes - antinuclei • 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? 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 Solar Modulation * Force field approximation? * Charge-dependent models?

  6. Transport equation in diffusion models Convection Destruction on ISM Diffusion CR sources: primaries, secondaries (spallations) Reacceleration Ionization, Coulomb, Adiabatic losses + Reacceleration

  7. I. Acceleration of GCRs: SNRs Predictions of supernova shock acceleration: (E)  E- = 2.0-2.1 (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

  8. 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)

  9. II. Propagation in the Milky Way • Diffusion on the inhomogeneities of the galactic magnetic field (~μG) * MHD waves with δB<<B  quasi-linear theory of plasma turbolence * Strongly anisotropic locally but isotropized on large scale * Parameterized by the diffusion coefficient: K(E)=KoβRδ (R=pc/Z|e| is the rigidity) • Cross sections: * Total (destruction) cross section * Production cross section • Convective wind outward the Galaxy (large-scale motions of the ISM) * VC constant or constant gradient

  10. Free parameters of a 2(3) D diffusive model • Diffusion coefficient: K(R)=K0bRd • Convective velocity: Vc • Alfven velocity: VA • Diffusive halo thickness: L • Acceleration spectrum: Q(E)=q0pa • K0, d, Vc, VA,L, (a)

  11. Characteristic times for various processes For a particle to reach z and come back (diffusion time) : tD≈ z2/K(E) At the same time, convection time: tC=z/VC A particle in z can come back to the disk only if tC<TD  zmax= K/VC N. B. The smaller the time, the most effective the process is For protons: escape dominates > 1 GeV E<1 GeV, convection and e.m. losses For iron: Spallations dominate for E<10 GeV/n

  12. Spatial origin of cosmic rays Some species have a local origin: Lmax~ √K(E)t Radioactive nuclei: trad = γτ0 =γ ln2 t1/2 @ GeV/n, K0~1028 cm2/s, t10Be = 1.5 Myr  lrad ~ 0.1 kpc Leptons: tloss = 300 Myr (1 GeV)/E @ E>10 GeV  le+e-~ 1 kpc

  13. Diffusive modelsJopikii & Parker 1970; Ptuskin & Ginzburg, 1976; Ginzburg, Khazan & Ptuskin 1980; Weber, Lee & Gupta 1992, .... • Some recently developped diffusive models: • 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) • .......... • 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 included shapes the model

  14. CRs in the heliosphere: Solar modulation CLIMAX neutron monitor The force field approximation might be imprecise for very accurate data Full equation Charge dependence?

  15. Results on Observed Prim/SecMaurin, FD, Taillet, Salati, ApJ (2001) Maurin, Taillet, FD A&A (2002) Systematic scan of the parameter space 6 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 spectrumα~2.0 No need for breaks in K(E) or Q(E)

  16. 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

  17. Secondary/primary nuclei: B/C & sub-Fe/Fe Moskalenko&Strong 2004 Maurin, Taillet, FD A&A 2002 No definite propagation model comes out High degeneracy of models Need more data around 1 GeV/n and at >20-30 GeV/n Jones, et al. ApJ (2001)

  18. Determination of diffusion coefficient? Predictions for various exp. configurations: δ: 0.3 0.45 0.6 0.7 0.85 DIFFERENT diffusion coefficients : K(E)= K0R Castellina & FD, 2005

  19. Effect of systematic errors Probability to discriminate between two different K(E)R by B/C data : 0.3-0.6 : 0.45-0.6 : 0.3-0.85 : 0.6-0.7

  20. 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?

  21. ANTIPROTONS IN COSMIC RAYSFD et al. ApJ (2001); BergstrÖm, EdsjÖ, Ullio, ApJ (1999); Bieber et al. PRL (1999); Moskalenko et al., ApJ (2002) • PCR+HISM • PCR+HeISM secondary antiprotons • aCR+HISM act as a background when looking • aCR+HeISM for exotic component • To calculate the secondary antiproton flux: • p and He in CRs(measured fluxes) • Nuclear cross sections(data + MonteCarlo) • Diffusion model(diffusive models)

  22. SECONDARY ANTIPROTON FLUX and DATA CR – target p - H p - He He - H He - He Total flux BESS 95-97, BESS 98, CAPRICE 98 FD et al, ApJ 2002 N.B. Propagation parameters: B/C best fit

  23. 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

  24. Antiproton/proton: data and models Predictions with the same semi-analytical Diffusive Model 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)

  25. Antiprotons From Relic Dark Matter particlesFD, Fornengo,Maurin,Salati,Taillet, PRD (2004), Bottino, FD, Fornengo, Salati PRD (1998) BergstrÖm, EdsjÖ, Ullio ApJ (1999) Source: • Number density Annihilation cross section Production spectrum Production takes place everywhere in the halo!! Solutions (still analytical in the 2D model) different from secondaries • - - Secondaries • ____ Primaries • m=60-100-300-500 GeV

  26. Antideuteron Flux From Astrophysical Processes • Proton and helium cosmic fluxes; antiproton calculated fluxes • Production and non-ann (tertiary) cross sections • Nuclear fusion: coalescence model, one parameter Pcoal = 79 MeV • the flux depends on (Pcoal)3 • Propagation in the MW from source to the Earth: • 2-zones semi-analytic diffusion model • Solar modulation: force field approximation • f= 0.5 MV for solar minimum

  27. Secondary antideuteronsFD, Fornengo, Maurin arXiv:0803.2460, PRD in press • Contributions to • Secondaries • p-p • p-He • He-H • He-He • H • He

  28. Secondary Antideuterons Propagation uncertainties Compatibility with B/C Nuclear uncertainties Production cross sections & Pcoal Production from antiprotons Non-annihilating cross sections

  29. Antiprotons - Antideuterons from DM AnnihilationsUncertainties due to propagation Antiprotons & Antideuterons Propagation Uncertainties Propagation uncertainties driven by L At lower energies, also effect from VC FD, Fornengo, Maurin 2008

  30. Antideuteron Signal-to-Background Dashed: MED m=10 m=100 m=500 MAX MED MIN m=50 GeV Low energy antideuterons have a high discrimination power

  31. Leptons in CRs: electrons and positrons • ELECTRONS are mostly primary: source and acceleration in SNR • ELECTRONS and POSITRONS are also secondary: p(He)+ H(He)  , K μ e Moskalenko & Strong, ApJ 1998

  32. Secondary positron/electron production Spallation of proton and helium nuclei on the ISM (H, He) • p+H  p++  p+0 & n++ (mainly below 3 GeV) • p+H  p+n+ + • p+H  X + K Different parameterizations of cross sections and incident p energy

  33. The positron source term Effect of proton flux determination - negligible Effect of production cross sections is not negligible (upper) (lower)

  34. Propagation of secondary positrons/electrons:relevance of energy lossses 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

  35. Energy losses for positrons/electrons Synchrotron and Inverse Compton* dominate *IC=scattering of e- on photons (starlight, infrared, microwave)

  36. Secondary 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

  37. Positron/electron: data and predictions Delahaye et al. A&A 2009, in press Yellow band: secondary positrons & propagation uncertainties Hard electrons: γ=3.34 There is no “standard” flux – dashed is B/C best fit

  38. FERMI Electrons and PAMELA positron fraction Models adjusted on Fermi e-, breaks at 4 GeV (acceleration) No Klein-Nishina losses

  39. Primary positrons and electrons from pulsars Pulsars can be the sources of energetic e+ and e-: pair production in the strong pulsar magnetoshpere Polar cap (disfavoured by recent Fermi data) and outer gap models • High energy e- are accelerated by the strong pulsar electric field • e- synchrotron radiate gamma rays • e+/e- are produced by pair conversion in strong magnetic fileds of the PSR or scattering off of thermal X-rays Profumo arxiv:0812.4457 Hooper, Blasi, Serpico, JCAP 2009

  40. FERMI Electrons and PAMELA positron fraction: contribution from local pulsars (d<3 kpc)(Grasso et. al 0905.0636) Good description of both e- and e+/(e+e-)

  41. Positron flux from relic neutralinos • Distribution of DM in the Galaxy (isoth., NFW, ...): r(r,z) • flux depends on r2 • Clumpiness? • Mass and annihilation cross section: effMSSM • overall normalization • Source term g(E): direct production or from secondary decays (from bb,WW,tt, ...)  Pythia MC • Propagation in the MW from source to the Earth: • 2-zones semi-analytic diffusion model • Solar modulation: force field approximation • f= 0.5 MV for solar minimum • NB The positron flux is more local than antiprotons or antideuterons depending on the propagation model: re+/rp+,D+ 0.1(Maurin&Taillet A&A 2003)

  42. Propagation of positron sources E0=1 GeV e=E/ E0 t=1016 s Delahaye, Lineros, Fornengo, FD, Salati DFTT7/2007 to appear Propagation models allowed by B/C

  43. Astroparticle Space Research • A way to build predictive models for standard cosmic rays • Propagation models are only “effective” models… • Uncertainties depends on the species, on energy • Propagation uncertainties: 10-100 for annihilating WIMPs antimatter • Is B/C the good prior? How much will systematics limit model building? • DM possible contributions are featurless, • except maybe for antideuterons • PAMELA, AMS, FERMI… are and will be a great ASTROPHYSICS factory!

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