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Cosmic-ray energy spectrum around the knee

Explore cosmic ray energy spectrum structures, chemical composition, interaction models, and interpretations at the 2nd HERD international workshop led by J. Huang in China. Discover insights on electron spectrum enhancement, high-altitude array merits, particle density separation, and the origin of the sharp knee from various experiments and analysis. Gain knowledge on the nonlinear effects in diffusive shock acceleration processes and the composition measurements in cosmic rays.

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Cosmic-ray energy spectrum around the knee

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  1. Cosmic-ray energy spectrum around the knee J.Huang Institute of high energy physics, Chinese Academy of Sciences China, Beijing 100049. The 2nd HERD international workshop ( 1-4 December 2013 , IHEP)

  2. Contents Global and fine structures seen in cosmic-ray energy spectrum Chemical composition of CRs Interaction model dependence in AS exp. Possible interpretation on the knee Enhancement of electron spectrum at several hundred GeV Summary J.Huang (The 2nd HERD international workshop)

  3. Tibet ASgamma experiment(50 TeV - 1017 eV) 7 r.l. Pb Iron Scint. Box Merit of high altitude • AS array at high altitude (4300m a.s.l.) • Tibet-III array:50000m2 with 789 scint. • YAC array: 500m2 with 124 scint. • MD array: 5000m2 with 5 pools of water Cherenkov muon D.s . • Measure:energy spectrum around the knee • and chemical composition using sensitivity of air showers to the primary nuclei through detection of high energy AS core. YAC The 2nd HERD international workshop

  4. Cosmic ray(P,He,Fe…) Particle density & spread Separation of particles Tibet-III: Energy and direction of air shower Tibet YACarray(Yangbajing Air shower Core arary) J.Huang (The 2nd HERD international workshop)

  5. Measure electron and muon size at Karlsruhe, Germany (near sea level). Energy spectra of 5 primary mass groups are obtained from two dimensional Ne-Nμ spectrum by unfolding method (P,He,CNO,Si,Fe). KASCADE experiment 40000 m2 1015-1017 eV

  6. Knee at 4 PeV dJ/dE∝E-γ γ=2.653.1 The results agree well between Tibet and KASCADE. All particle spectrum. J.Huang (The 2nd HERD international workshop)

  7. All-particle spectrum measured by Tibet ASgamma from 1014 ~1017eV (ApJ 678, 1165-1179 (2008)) 7 J.Huang (The 2nd HERD international workshop) 5/ 31

  8. Energy spectrum around the knee measured by many experiments TibetKASCADEHEGRA CASA/MIABASJEAkeno DICE J. Huang (ISVHECRI2012, Berlin, Germany)

  9. Normalized spectrum J.Huang (The 2nd HERD international workshop)

  10. A sharp knee is clearly seen (ApJ 678, 1165-1179 (2008)) What is the origin of the sharp knee? There were many models: nearby source, new interaction threshold, etc. In the following, I would introduce our two analyses for the origin of the sharp knee. 10 J.Huang (The 2nd HERD international workshop) 6/ 31

  11. What is the origin of the sharp knee? Cannot be explained by propagation effect (diffusion during long confinement time in the galaxy) Additional component? Astrophysical scenario : nearby source Particle physics scenario : beyond STD model Acceleration mechanism? High acceleration efficiency in diffusive shock acceleration (DSA) leads hard source spectrum at the acceleration limit due to nonlinear effect. J.Huang (The 2nd HERD international workshop)

  12. Nonlinear effect in DSA process Malkov, E. & Drury, L.O.C. 2001, Rep. Prog. Phys. 64, 429 Ptuskin, V.S., & Zirakashvili, V.N., 2006, Adv. Space Res., 37, 1898 Assume source spectrum as Ref . (M.Shibata, J.Huang et al. ) ApJ,716,1076–1083 (2010) J.Huang (The 2nd HERD international workshop)

  13. Composition measurement • Ne-Nμ correlation -- μrich showers are induced • by heavy primary (traditional method) • Detection of high energy core selects AS induced • by light elements (P,He) -- Tibet • Xmax -- fluorescence technique at VHE • Model dependence comes from and . Sensitivities to the primary chemical composition used in AS exp. are: J.Huang (The 2nd HERD international workshop)

  14. KASCADE QGSJET01 J.Huang (The 2nd HERD international workshop)

  15. KASCADE SIBYLL

  16. KASCADE P,He,CNO compared with direct observations J.Huang (The 2nd HERD international workshop)

  17. KASCADE Si, Fe compared with direct observations J.Huang (The 2nd HERD international workshop)

  18. Proton and Helium by Tibet QGSJET All All P He SIBYLL All All He P

  19. P+He spectrum J.Huang (The 2nd HERD international workshop)

  20. Model dependence Tibet concludes : “Knee is dominated by nuclei heavier than helium. Tibet〜30% All All He P KASCADE : QGSJET analysis : helium dominance SIBYLL analysis : CNO dominance KASCADE〜twice All All P He

  21. L3+C muon spectrum compared to MC model

  22. Interaction model dependence in Tibet ASgamma experiment(Some preliminary results from YAC1 data samples) 90 TeV 30 TeV 260 TeV 1800 TeV • 1) The shape of the distributions of sumNb are consistent between the YAC-I data and simulation data in all four cases, indicating thatform *10TeV to 1800 TeV, the particle production spectrum of QGSJET2 and SIBYLL2.1 may correctly reflect the reality within our experimental systematic uncertainty of a level about 10%. J.Huang (The 2nd HERD international workshop)

  23. 90 TeV 30 TeV 260 TeV 1800 TeV Comparison of event absolute intensities between Expt. and MC J.Huang (The 2nd HERD international workshop)

  24. LHCf experiment

  25. Primary (P+He) spectra obtained by (YAC1+Tibet-III) (P+He) “ knee”: 400TeV Most new interaction models (EPOS-LHC, QGSJETII-04 ) has been used ! The interaction model dependence is less than 25% in absolute intensity, and the composition model dependence is less than 10% in absolute intensity.

  26. Our results agree well with direct experiment Preliminary (P+He) “ knee”: 400TeV

  27. Common results between Tibet and KASCADE Knee is located at 4 PeV. (γ=2.653.1) Steep spectrum of protons at the knee (protons are not the majority). Fraction of heavy nuclei increases with increasing energy. J.Huang (The 2nd HERD international workshop)

  28. Direct observations Cosmic ray energy spectrum below the knee has been considered to follow simple power law. Recently, hardening of the spectrum has been reported by ATIC and CREAM @ 200 GeV/n. J.Huang (The 2nd HERD international workshop)

  29. ATIC >200 GeV/n Hardening of the energy spectrum A.D.Panov et al., Arxiv:astro-ph/0612377v1 (2006) J.Huang (The 2nd HERD international workshop)

  30. CREAM data: P&He spectra are not the same H.S.Ahn et al., ( CREAM collaboration )ApJ, 714, L89, (2010) CREAM suggests that: 1) Their fluxes are significantly higher than the extrapolation of a single-power law fit to the low energy spectra. 2) Different types of sources or acceleration mechanisms? (e.g., Biermann, P.L. A&A, 271, 649, 1993) He γHe=2.58±0.02 P γp= 2.66 ±0.02

  31. Heavy dominance toward the Knee(TeV spectra are harder than spectra < 200 GeV/n) ATIC CREAM A.D.Panov et al., Arxiv:astro-ph/0612377v1 (2006) H.S.Ahn et al., ApJ, 714, L93 (2009)

  32. Spectrum of nuclei by CREAMas a function of energy/particle • Simple extrapolation • does not work to fit • the knee energy region. • Change of power • index is required for • all elements again. J.Huang (The 2nd HERD international workshop)

  33. Extrapolation of CREAM data using broken power law cannot fit to the sharp knee Need extra component Assumptions: Eb(p)=300 TeV, Rigidity dependence of break point for nuclei, Eb(Z)=Zx300 TeV Δγ=0.4 J.Huang (The 2nd HERD international workshop)

  34. Possible knee scenario ScenarioA ScenarioB Hard src spect? Nearby src? J.Huang (The 2nd HERD international workshop)

  35. Primary electrons High energy electrons cannot travel long distance due to their energy loss proportional to E2. The energy spectrum can show the contribution of nearby sources (say ~1kpc) or new physics such as dark matter decay or beyond STD model. ATIC, Pamela, Fermi-LAT, H.E.S.S. J.Huang (The 2nd HERD international workshop)

  36. The ATIC Electron Results Exhibits a “Feature” J.Chang et al, Nature, 456,362,(2008) Possible candidate local sources would include supernova remnants (SNR), pulsar wind nebulae (PWN) and micro-quasars. J.Huang (The 2nd HERD international workshop)

  37. Anomalous positron abundance V.Mikhailov et al.ESCR 2010, Turku, 3 August O.Adriani et al., Nature, 458,607(2009)

  38. Fermi-LAT

  39. Relation between Fermi e± and extra component at the knee? (W.Bednarek and R.J.Protheroe ,2002,APh) ? PeV nuclei + target （ ＊10 TeV/n) π0 γ ＊100GeV e± This may be quite possible scenario. J.Huang (The 2nd HERD international workshop)

  40. Summary Knee is located at 4 PeV exhibiting sharp structure with Δγ=0.4±0.1 Disagreement of chemical composition between KASCADE and Tibet is due to strong interaction model dependence of Air Shower MC which is larger in KASCADE experiment. Extrapolation of CREAM data using simple broken power law formula cannot fit to the AS data at the knee. J.Huang (The 2nd HERD international workshop)

  41. Tibet data and ATIC/CREAM spectra of nuclei suggests knee is dominated by heavy nuclei, which can be attributed to nearby source dominated by heavy element (Pulsar?) or hard cosmic-ray source spectrum. • Enhancement of electron spectrum at hundreds GeV range might be correlated with the structure of cosmic-ray spectrum. --- possible contribution of nearby sources? • Further study of the chemical composition up to the knee and beyond is necessary to solve the problem.  HERD planandindirect observations (Tibet ASgamma, KASCADE-G, LHAASO, Grapes, TA-TAIL).

  42. High Energy cosmic-Radiation Detection (HERD) Proton Helium Expected HERD ( 2 yr) results : C (Please see Dr. Xu Ming’s talk) Iron

  43. The New Tibet hybrid experiment (YAC+Tibet-III+MD)

  44. (Large High Altitude Air Shower Observatory) LHAASO

  45. Thank you for your attention !!

  46. TRACER M.Ave et al., ApJ, 678, 262 (2008)

  47. KASCADE all particle spectrum

  48. Highest energy data

  49. Electron and Positron from Dark Matter Decay Decay Mode: D.M. -> l+l-ν Mass: MD.M.=2.5TeV Decay Time: τD.M. = 2.1x1026 s Expected e-+e+ energy spectrum by CALET observation Expected e+/(e-+e+) ratio by a theory and the observed data Observation in the trans-TeV region Dark Matter signal Ibarra et al. (2010) July 21, 2010 49

  50. A : Find candidate of nearby source. B : Does break point show rigidity dependence? Chemical composition after the knee: A : becomes lighter between 1016 and 1017 eV. KASCADE-GRANDE claimed second knee at 8x1016 eV. B : Heavy dominance up to the maximum energy of GCR. Discriminating scenario A and B

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