I On Atmospheric Antiprotons in Cosmic Ray Study

I. On Atmospheric Antiprotons in Cosmic Ray Study II. Te. V-band Gamma Rays in III. RX J 1713. 7 -3946 Ching-Yuan Huang (黄庆元) 20 October 2010 Institute of Theoretical Physics Chinese Academy of Science 1

Section I: Cosmic Rays 2

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 e. V (100 Me. V) to 1020 e. V (100 Ee. V) 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 3

Cosmic Ray Composition and Spectrum Solar Modulation • 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 (200 Te. V) (simple power law) Non-thermal! 4

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

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

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

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

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

Section II: Atmospheric Antiprotons 10

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! • possible exotic origin: - annihilation of SUSY Dark Matter (Neutralino χ) - evaporation of Primordial Black Holes (PBH) 11

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

Challenge for Cosmic Antiproton Detection • measured antiprotons in Earth experiments are actually a composition exp. measured 2 nd atmospheric 2 nd Galactic cosmic primary SUSY Correction of atmospheric antiprotons onto experiments is absolutely required! PBH 13

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 ↓ plan e geomagnetic field line rial bit Model of Atmosphere Equ ato Po le or AM S 2) Interaction CR+A→n±, p±+X… 5) End of propagation: escape, collision/slowing down/absorbed… 14

Antiproton Experiments and Altitudes 400 km to measure pure cosmic antiproton flux (i. e. , no atmospheric component) AMS (Discovery ST 591) Ans: quite doubtful! 40 km 3 km to measure antiproton flux at Top of Atmosphere (TOA) mountain level exp. very unusual (BESS ’ 99 exp. )! 15

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

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? AMS@400 km (Huang ’ 03 PRD) 17

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/quasitrapped charged particles in Earth magnetic field! 18 (on AMS acceptance) (Huang ’ 03 PRD)

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

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

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

Section II: Te. V-band Gamma Rays of RX J 1713. 7 -3946 22

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 23

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…) 24

γ Induced Air Shower Observed at Ground 25

RX J 1713. 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 (HESS ’ 06) • X-ray time variability → study SNR magnetic field strength 26

Te. V-Band Spectrum of RX J 1713. 7 -3946 • Leptonic models (bremsstrahlung or Inverse Compton) requires unusually weak magnetic field! • Data with E ~ Me. V to 10 Te. V is needed for the puzzle! 27

Best Fitted Spectrum of RX J 1713. 7 -3946 • HEP event generator to simulate full picture of cosmic-ray hadronic interactions • considered full picture of γ -ray decays = 22. 4 for 22 DOF (-) spectral curvature strongly suggested (with CL > 95%)! (Huang et al. , ’ 07) 28

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! (Amato & Blasi ’ 06) (Ellison et al. , ’ 00) 29

X-Ray Emission Variability in of RX J 1713. 7 -3946 (2000) Chandra Observation (2005) (2006) (Uchiyama et al. , ‘ 07) • unique information of magnetic field in particle acceleration region! • Rapid variability implies shorter timescales and amplification of B field in SNR shell. 30

Synchrotron Radiation of RX J 1713. 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-m. G field only possible with very limited fraction! (Huang et al, ’ 08) 31

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! 32

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

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 p. A 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 34

Summary of Te. V Gamma Rays • • • easy-to-use production matrices for cosmic ray interactions and decays; favored in hadronic model for SNR such as RX J 1713. 7 -3946 no evidence for standard models of CR modified shock accelerations; γ-ray data with energy E: Ge. V~ Te. V is needed to test cosmicray acceleration model; the multi-m. G magnetic field proposed for X-ray flux variations is very limited in RX J 1713. 7 -3946 proposed a promising experiment with data accumulation over 5 -10 years at E(μ)~ few Te. V, or E(ν) ~ 10 Te. V, to test origin of Te. V γ-rays 35