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Ching-Yuan Huang ( 黄庆元 ) 20 October 2010

On Atmospheric Antiprotons in Cosmic Ray Study TeV-band Gamma Rays in RX J1713.7-3946. Ching-Yuan Huang ( 黄庆元 ) 20 October 2010. Institute of Theoretical Physics Chinese Academy of Science. Section I: Cosmic Rays. Something about Cosmic Rays.

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Ching-Yuan Huang ( 黄庆元 ) 20 October 2010

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  1. On Atmospheric Antiprotons in Cosmic Ray Study • TeV-band Gamma Rays in • RX J1713.7-3946 Ching-Yuan Huang (黄庆元) 20 October 2010 Institute of Theoretical Physics Chinese Academy of Science

  2. Section I: Cosmic Rays

  3. Something about Cosmic Rays • High energy charged particles arriving at Earth from outer space • Discovered in 1912 • Natural source for new particle discovery (until 1953) • Energy: 108 eV (100 MeV) to 1020 eV (100 EeV) • Time scale contained in galaxy: can be as long as 1010 years - Messenger of non-thermal Universe • Interest: • origin:Supernova Remnants? Black Holes? Dark Matters? • Pulsar? Active Galactic Nuclei?... • - acceleration:B field? shock acceleration?... • - transport/interaction

  4. cosmic ray compositions: - 86% p; 12% α - 2% e - 1 % C, N, O,Li, Mg, Si, Fe nuclei - small amount of (~ p) • Cosmic Ray (CR) Spectra Solar Modulation (simple power law) (200 TeV) Non-thermal! Cosmic Ray Composition and Spectrum

  5. regimes in CR spectrum knee ankle GZK cutoff 3 Regimes in Cosmic Ray Spectrum

  6. z halo ⊙ disc r halo Cosmic Rays in Galaxy • diffusion process in large scale halo under galactic magnetic irregularities; • physics involved: production, (re)-acceleration, energy loss, decay, interaction, convection, diffusion, escape, fluctuation...

  7. Cosmic Rays in Solar System and Earth Both against low energy cosmic rays!

  8. (shaded: forbidden; white: allowed) Allowed/Forbidden Regions • critical case: b (impact parameter)= -1, allowed regions linked • Geomagnetic cutoff arises from Earth magnetic field!

  9. Cosmic Rays in Earth Atmosphere unique technique for detection of cosmic-ray particles with E > 200 TeV, due to detector limitation!

  10. Section II: Atmospheric Antiprotons

  11. possible exotic origin: • - annihilation of SUSY Dark Matter (Neutralino χ) • - evaporation of Primordial Black Holes (PBH) Why Antiprotons/Atmospheric Antiprotons? • interest of origin (discovered in 1979) • - galactic origin:secondary product from interactions • between cosmic rays and interstellar medium (called • galactic, galactic secondary) Not abundant enough to explain the exp. detections!

  12. ID window by Peak at 2 GeV SUSY DM and PBH identification window exists in window E< 1 GeV! Antiproton Spectra from Different Sources GeV) (SUSY model for

  13. Challenge for Cosmic Antiproton Detection • measured antiprotons in Earth experiments are actually a composition Correction of atmospheric antiprotons onto experiments is absolutely required!

  14. Schematics of Simulation Model 1) Cosmic Ray distribution (natural abundance); incoming particle propagation in Earth magnetic field 3) Propagation of secondaries 4) Counting when crossing orbit altitude ↑and ↓ 2) Interaction CR+A→n±,p±+X… AMS orbit Model of Atmosphere Pole geomagnetic field line Equatorial plane 5) End of propagation: escape, collision/slowing down/absorbed…

  15. to measure pure cosmic antiproton flux (i.e., no atmospheric component) AMS 400km (Discovery ST591) Ans: quite doubtful! to measure antiproton flux atTop of Atmosphere (TOA) 40km 3km very unusual (BESS ’99 exp.)! Antiproton Experiments and Altitudes mountain level exp.

  16. BESS ’98@38km CAPRICE ’98@36km CR He contribution CR He contribution (Huang ’03 PRD) Antiproton Flux at TOA by Balloon Exp. Good agreement with previous calculations!

  17. (Huang ’03 PRD) AMS@400km Antiproton Flux Measured by AMS • Atmospheric correction is always needed, even for space experiments! • pure (nearly) measurement possible only in (sub)polar regions! • upward/downward particles compatible. Why?

  18. (on AMS acceptance) (Huang ’03 PRD) Integrated Antiproton Flux • At balloon altitudes, only ↓particles can be detected! (totally detector effect) • At space altitudes, ↓and ↑ charged particles are of the same order, unless in (sub)polar regions. Existence of trapped/quasi-trapped charged particles in Earth magnetic field!

  19. (Huang ’03 PRD) Charged Particle Trajectory in Earth Multipole • particles in low latitude regions with extremely complicated trajectories, contributing large crossing multiplicity! • Particles at high altitudes or with high kinematics can be trapped by Earth!

  20. good probe to test cosmic-ray transport model! • Result was confirmed by BESS 1999 experiment! (Sanuki, ’03 PLB) Antiproton Measurement at Mountain Level • Flux magnitude at this level is small but still detectable by current exp. detectors. • Antiprotons are purely atmospheric at such altitudes. 400km 40km 3km

  21. discrepancy from data in other models usually used (Bowen ’86; Stephens ’93) • result confirmed by BESS exp.! (Huang ’03 PRD, Huang ’07 Astropart. Phys.) Antiproton Flux at Mountain Level

  22. Section II: TeV-band Gamma Rays of RX J1713.7-3946

  23. Gamma-Ray Astrophysics • probe of the non-thermal Universe • neutral in charge, high penetrating nature of emissions, as a powerful tool to study cosmic-ray sources in γ-ray domain • Broad waveband γ-ray observation presents clear physical characters: • - Synchrotron • - Bremsstrahlung • - hadronic interactions (and decays) • - Inverse Compton Scattering

  24. Gamma-Ray Astrophysics (Ultimate Purpose) • understand cosmic-ray origin, acceleration, propagation… understand the γ-ray background (Big Bang, DM, CMB…) Need to unmask the γ-ray foreground! (γ-ray foreground: cosmic-ray source emissions, diffuse radiation in transport…)

  25. γ Induced Air Shower Observed at Ground

  26. (HESS ’06) RX J1713.7-3946 Observation • young shell-type SNR • → study cosmic-ray time evolution near source • dense molecular gas along line of sight • → test for hadronic/leptonic model for cosmic-ray acceleration • X-ray time variability • →study SNR magnetic field strength

  27. TeV-Band Spectrum of RX J1713.7-3946 • Leptonic models (bremsstrahlung or Inverse Compton) requires unusually weak magnetic field! • Data with E ~ MeV to 10 TeV is needed for the puzzle!

  28. = 22.4 for 22 DOF (-) spectral curvature strongly suggested (with CL > 95%)! (Huang et al., ’07) Best Fitted Spectrum of RX J1713.7-3946 • HEP event generator to simulate full picture of cosmic-ray hadronic interactions • considered full picture of γ-ray decays

  29. (Amato & Blasi ’06) (Ellison et al., ’00) Shock Modification for Cosmic Rays • non-linear shock modification arises due to the dynamical reactions of accelerated particles on the shocks • Models predict continuous hardening spectra with a (+) spectral curvature!

  30. (2000) (2005) (2006) (Uchiyama et al., ‘07) Chandra Observation X-Ray Emission Variability inof RX J1713.7-3946 • unique information of magnetic field in particle acceleration region! • Rapid variability implies shorter timescales and amplification of B field in SNR shell.

  31. (Huang et al, ’08) Synchrotron Radiation of RX J1713.7-3946 • full picture of e-/e+ production and decays in CR interactions • more severe limits on B, α; • The non-thermal X-ray emission must originate from primary e-/e+! • multi-mG field only possible with very limited fraction!

  32. Cosmic-Ray Neutrinos • background for ν Astrophysics • tool to study on CP-violation (neutrino oscillations) in Standard Model (atmospheric ν anomaly…) • accompanied product of hadronic γ-rays Neutrinos as the supplement tool to study hadronic and leptonic scenario in cosmic-ray particle origin/acceleration!

  33. -Induced μ Rate of HE γ-Ray Sources • ν full mixing assumed: (Huang et al, ’08) • IceCube-like detector assumed experiment with data accumulation over 5-10 yrs at Eμ~ few TeV, or Eν~10 TeV to test hadronic origin of TeV γ-rays!

  34. Summary on Atmospheric Antiprotons • a tool allowing to calculate the proton and atmospheric antiproton flux in the Earth environment: • - developed antiproton production cross section in pp and pA collisions; • - shown the atmospheric antiproton correction is always required; • - model agreed with proton flux from sea level to TOA • Antiprotons at low altitudes provides a tool to verify models and calculations. • approved understanding of particle dynamics in Earth environment

  35. Summary of TeV Gamma Rays • easy-to-use production matrices for cosmic ray interactions and decays; • favored in hadronic model for SNR such as RX J1713.7-3946 • no evidence for standard models of CR modified shock accelerations; • γ-ray data with energy E: GeV~ TeV is needed to test cosmic-ray acceleration model; • the multi-mG magnetic field proposed for X-ray flux variations is very limited in RX J1713.7-3946 • proposed a promising experiment with data accumulation over 5-10 years at E(μ)~ few TeV, or E(ν) ~ 10 TeV, to test origin of TeV γ-rays

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