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Nicola Tomassetti

Origin of the Spectral Hardening in Galactic Cosmic Rays. Nicola Tomassetti. INFN Perugia. ECRS July 2012 Moscow. Spectral Features in Primary Cosmic Rays. CR data on primary nuclei indicate three remarkable features. 1. Hardening effect Remarkable change in slope above ~100 GeV/n

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Nicola Tomassetti

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  1. Origin of the Spectral Hardening in Galactic Cosmic Rays Nicola Tomassetti INFN Perugia ECRS July 2012 Moscow

  2. Spectral Features in Primary Cosmic Rays CR data on primary nuclei indicate three remarkable features 1. Hardening effect Remarkable change in slope above ~100 GeV/n 2. Discrepant hardening Different elements (p, He…) exibith different spectral slopes 3. Another PAMELA anomaly? Sharp structures in p and He spectra at 100 GV (the dip & the break). NL-DSA concavity? Multi-source? Could be a signature of DSA/SNR Malkov et al 2012 – Ohira et Ioka 2011 Likely “extrinsic”, e.g. from local source (Erlykin &Wolfendale Aph 2012) To be confirmed experimentally ECRS 2012 - Moscow  N. Tomassetti - INFN Perugia [ 01 / 14 ]

  3. Spectral Features in Primary Cosmic Rays “These data challenge the current paradigm of cosmic-ray acceleration in supernova remnants followed by diffusive propagation in the Galaxy”. Adriani et al. Science 2011 “…We rather think that the SNR paradigm is in fact more complex than usually assumed in doing these claims, and that its consequences are not yet so well understood as sometimes people would like to believe”. Blasi & Amato JCAP 2012 ECRS 2012 - Moscow  N. Tomassetti - INFN Perugia [ 02 / 14 ]

  4. Fermi/GALPROP results Ackermann et al ApJ april 2012 [1202.4039] Inner Galaxy Halo Pion decay Inverse compton High-energy gamma-ray data are under(over)-predicted in the inner Galaxy (outer halo) Cosmic-ray spectral variations?? DGE Bremsstrahlung Total Isotropic EGB+ RIB Point sources ECRS 2012 - Moscow  N. Tomassetti - INFN Perugia [ 03 / 14 ]

  5. The CR/SNR Paradigm (and problems) Basic predictions DSA@SNRs: power-law source spectra (α~ 2.0 – 2.2) QLT: power-law diffusion regime (δ~ 0.3 - 0.7) Expected CR spectra at Earth (E>>GeV/n) Data say • Primary CR data: α+δ = 2.7 (Depending on the element) • Anisotropy data: δ < 0.3  α > 2.4? (Small diffusivity. Steep source spectra?) • Gamma-ray data: α < 2.3  δ > 0.4 ? (Still too hard for anisotropy) • Sec/Pri ratios: δ = 0.2 - 0.8 (Need of data at high energy) • Stocasticity (Blasi & Amato JCAP 2012) • Non-linear DSA acceleration (e.g. Caprioli JCAP 2012) • … ECRS 2012 - Moscow  N. Tomassetti - INFN Perugia [ 04 / 14 ]

  6. The Magnetic Halo All CR propagation models assume the same turbulence spectrum in the whole halo  same rigidity dependence for K(R) everywhere! Halo Propagation region BUT…WHERE THE TURBULENCE COME FROM? L ~ 5 kpc Disk Contains SNRs and ISM matter 2h ~ 200 pc SNRs Cosmic ray sources CRs Erratic motion in turbulent B-field Free escape boundary ECRS 2012 - Moscow  N. Tomassetti - INFN Perugia

  7. The Magnetic Halo

  8. The Magnetic Halo Erlykin & Wolfendale J.Phys.G 2002 •  Large irregularities • small wave numbers • soft turbulence spectrum • hard diffusivity (small δ) INNER HALO SNRs are the source of turbulent motion OUTER HALO No SNRs! Turbulence is driven by CRs themselves.  steeper diffusivity (large δ)

  9. A Two-Halo Model of CR Diffusion NT ApJ 715 L13 [astro-ph/1204.4492] NOT separable into space and energy terms! diffusion sources interactions ECRS 2012 - Moscow  N. Tomassetti - INFN Perugia [ 08 / 14 ]

  10. A Two-Halo Model of CR Diffusion NT ApJ 715 L13 [astro-ph/1204.4492] NOT separable into space and energy terms! Non-separability  deviation from power-law ECRS 2012 - Moscow  N. Tomassetti - INFN Perugia [ 08 / 14 ]

  11. Results for primary CR spectra NT ApJ 715 L13 [astro-ph/1204.4492] TeV hardening predicted in all CR nuclei spectra ECRS 2012 - Moscow  N. Tomassetti - INFN Perugia [ 09 / 14 ]

  12. Results for secondary/primary ratios B/C ratio Hardening effect for sec/pri ratios. Barely suggested by data. Detecting a spectral hardening in the B/C ratio would be a signature for its diffusive origin. ECRS 2012 - Moscow  N. Tomassetti - INFN Perugia [ 10 / 14 ]

  13. Model implications in open problems of CR physics CR spectral hardening observed at > 100 GeV/n This model: CR spectra must harden High energy anisotropy weakly E-dependent above E=TeV This model: Anisotropy must flatten at high energy B/C and pbar/p ratios seem to flatten at high energy This model: Sec/pri ratio must flatten at high energy Diffuse γ-ray spectra appear steeper in the outer halo This model: spectra must be steeper in the outer halo ECRS 2012 - Moscow  N. Tomassetti - INFN Perugia [ 11 / 14 ]

  14. Alpha Magnetic Spectrometer • H/He ratio VS rigidity up 1 TV. • Confirm or disprove the PAMELA structures (dip/ankles) • Give spectral indices, break rigidities, sharpness parameters. • Spectral structures search in Z>2 nuclei (C, O, Si, Fe) • Sec/Pri ratio up to TeV/n energies (Li/C, B/C, F/Ne, pbar/p) • Other channels: e- / isotopes / gamma AMS on orbit - from STS-134 to ISS AMS Hadronic Tomography p/He ratio ECRS 2012 - Moscow  N. Tomassetti - INFN Perugia [ 12 / 14 ]

  15. Alpha Magnetic Spectrometer AMS A simple discrimination scheme is as follows: (see also Vladimirov et al 2012 ApJ astro-ph/1108.1023) AMS Thoudam et al 2012 Zatsepin et al 2012 Erlykin & W. 2011 Yuan et al 2011 Ptuskin et al 2011 Biermann et al 2010 … This Model need of high energy data: AMS need of precision data: AMS ECRS 2012 - Moscow  N. Tomassetti - INFN Perugia [ 13 / 14 ]

  16. Conclusions if everybody does their job… …new results and new understanding will soon arrive Thank you ECRS 2012 - Moscow  N. Tomassetti - INFN Perugia [ 14/ 14 ]

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