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

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). Spectral Features in Primary Cosmic Rays CR data on primary nuclei indicate three remarkable features 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 N. Tomassetti - INFN Perugia ECRS Moscow [ 01 / 14 ]

“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 Spectral Features in Primary Cosmic Rays N. Tomassetti - INFN Perugia ECRS Moscow [ 02 / 14 ]

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

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

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

The Magnetic Halo

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

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

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

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

Results for secondary/primary ratios 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. B/C ratio N. Tomassetti - INFN Perugia ECRS Moscow [ 10 / 14 ]

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

Alpha Magnetic Spectrometer AMS Hadronic TomographyAMS on orbit - from STS-134 to ISS 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 N. Tomassetti - INFN Perugia ECRS Moscow p/He ratio [ 12 / 14 ]

A simple discrimination scheme is as follows: (see also Vladimirov et al 2012 ApJ astro-ph/ ) need of precision data: AMS origin of the CR hardening Pri spectra Sec spectra Pri/Sec ratios from nearby sourcesYesNo from accelerationYes No from propagationYes need of high energy data: AMS This Model Thoudam et al 2012 Zatsepin et al 2012 Erlykin & W Yuan et al 2011 Ptuskin et al 2011 Biermann et al 2010 … Alpha Magnetic Spectrometer AMS AMS N. Tomassetti - INFN Perugia ECRS Moscow [ 13 / 14 ]

Conclusions if everybody does their job… …new results and new understanding will soon arrive N. Tomassetti - INFN Perugia ECRS Moscow Physicists provide: AMS provides: Universe provides: data analysis and theory raw data cosmic rays Thank you [ 14/ 14 ]