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Study on the Spatial-Dependent Propagation of Galactic CRs Yiqing Guo, Hongbo Hu, Zhen

This study explores the spatial-dependent propagation of cosmic rays in the galaxy and its contribution to the spectral hardening and secondary particles. Latest observational results and the possible origin of the hardening spectra are discussed. The study also examines the anisotropy and the ratio of secondary to primary cosmic rays.

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Study on the Spatial-Dependent Propagation of Galactic CRs Yiqing Guo, Hongbo Hu, Zhen

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  1. Study on the Spatial-Dependent Propagation of Galactic CRs Yiqing Guo, Hongbo Hu, Zhen Tian & Chao Jin IHEP,CAS 2016.12.1 @Torino,Italy (7th workshop on Air Shower Detection at High Altitude)

  2. Content CR propagation in conventional model Latest observational results Hardening spectra contribute to secondary particles 4. Possible origin of hardening spectra: spatial-dependent propagation of CRs 5. Conclusion

  3. CR propagation in the conventional model

  4. Spectra of CRs • Energy: • Range:109 – 1020 eV • High Enegy: 3×1020eV • Spectral: power law • age：~107yrs • Energy density：1eV/cm3 • power：1041ergs/s • structures： 0. ~200 GeV: Hardening • ~4 PeV:“knee” • ~30PeV:“2nd knee” • ~4 EeV: “ankle” • ~40EeV: GZK cut-off Space Ground Hot Topic: 1. Where do CRs come from?  Origin 2. How do CRs gain energy?  acceleration 3. How do CRs arrive earth?  propagation galactic Extra-galactic 2nd particles except e-

  5. CR Propagation: standard model sources (SNR, nuclear reactions…) diffusion convection ψ(r,p,t) – density per total momentum diffusive reacceleration convection E-loss radioactive decay fragmentation PPT com fromIgor V. Moskalenko (Stanford U.)

  6. Spectrum in Conventional Propagation Model • Stable Solution: • = 0 • “Isotropy” Propagation: • DXX = βD0(ρ/ρ 0)-δ • 3. CR Injection: q(r,E) = J0*E-β • 4. Getsingle power index “in Whole Galaxy”: • (1) Primary CRs： • F(E) ~ q(r,E)/DXX~ JE-β-δ • (2) Ratio of 2nd to Primary：~ E-δ • (fast decrease with energy) How about Observation? 8

  7. Latest Observations: • Primary CRs • Secondary CRs

  8. Spectral Hardening of Primary CRs AMS02 Precise Measurement: 2015, 114, 171103

  9. Spectral Hardening of Primary Electron X. Li, et al., 2015, PhLB, 749,267 Q. Yuan, et al., 2013, PhLB, 727,1-7

  10. How about secondary particles?

  11. Positron Excess Diffuse Flux Origin: DM, Pulsar, CRs and others? 11

  12. B/C has break at hundreds of GeV?

  13. Galactic diffuse Gamma Ray Break @ ~10 GeV ApJ,2009,ZhangJ Ackermann,ApJ,2012,750,3 A&A,2012,538,71

  14. Diffuse Gamma Ray at Halo “excess”is only at Disk and consistent with Conventional model at halo！ Ackermann,ApJ,2012,750,3

  15. IceCube Neutrino Neutrino: 1. Total Number: 54 2. Background: ~22 3. Astrophysical one: ~32 4. Significance: 6.5σ Arriving Direction: 1. Isotropy(ExtraGalactic): PRL,2014,arxiv:1405.5303 2. Some ones: Disk Excesses？ (Galactic Origin)? arXiv:1412.1690 Aguilar , RICAP,2016

  16. IceCube Neutrino Spectrum Including TeV ：2.46 (2) From 30TeV: 2.0-2.3 (3) Galactic pp-collision: ~2.6

  17. Two component spectrum of CRs (Tomassetti, 2012, ApJ, 752,13) Two Components : Hard Component Soft Component

  18. Hardening Component Contributes to the secondary CRs

  19. Galactic diffuse Gamma Rays By Adopting the Hardening Component, the Diffuse gamma-rays at Galactic disk can be well reproduced! Large uncertainties at high Energy and hope LHAASO can fix it !

  20. Diffuse Neutrino • Adopting the Hardening Component can Contribute ~60% • IceCube Neutrino（depending the energy extrapolate method!） • (2) Anisotropy: most of those neutrinos come from galactic disk.

  21. Galactic Neutrino in Conventional Model • pp-Collision~10% in Conventional propagation model  Galactic Contribution at 10%--60% • We Hope that LHAASO can test our model and “Fix” the Galactic Contribution ! • Guo Y.Q.,Hu H.B., Yuan Q., et al., ApJ, 2014, 795,100

  22. excess The Ratio of 2nd to primary CRs will decrease with energy. After adopting the Hardening Component, the ratio is “flat” distribution at high Energy

  23. Ratio of B/C has break at ~100 GeV and • become dominant ~TeV. • We hope that AMS02 and DAMPE/CALET • can test our model in future.

  24. One possible origin of Hardening Component:  Spatial-Dependent Propagation

  25. Spatial-Dependent Propagation(Jin C., et al., arXiv:1504.06903) (1) ：CRs Propagation In Convention Model (2) Propagation in Two Halo Model：

  26. Further Study：Considering source distribution (Guo Y.Q., Tian Z., Jin C., 2016，ApJ, 819,54)

  27. Spatial-Denpendent Propagation • Reproduce spectral hardening • of primary CRs • Reproduce the “flat” pbar/p ratio • at high energy as AMS02 results。 • Expect the break of B/C at TeV • and can be tested by AMS02/ • DAMPE in future.

  28. Primary Nuclei and Electron Spectral Hardening (Jin C., et al., arXiv:1504.06903) We can reproduce the spectral hardening of primary nuclei and electron in one self-consistent physical picture.

  29. Anisotropy Problems Our result The expected anisotropy in Spatial-dependent propagation is consistent with experimental results! 25

  30. Conclusion • Hardening Component of CRs have important contribution to 2nd CRs • One possible origin of Hardening Component is the Spatial-Dependent propagation of CRs. • The Spatial-Dependent Propagation can give self-consistent picture for spectral-hardening, “flat” distribution of pbar/p and • expect the break at above TeV for B/C • We hope that AMS02, DAPME and LHAASO can test our model in future!

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