Nicolò Masi Bologna University and INFN - 31 May 2016
Topics 1. Towards a unified picture of CRs production and propagation: Astrophysical uncertainties with GALPROP Local Interstellar Spectra: AMS-02 vs Voyager 2. AMS-02 good candidates for Dark Matter space search 3. AMS-02 measurements: How we can read them and how we can procede beyond the orthodoxy
The Propagation Scheme in the Milky Way Diffusion Reacceleration Energy Loss in ISM Fragmentation Source Convection Adiabatic Expansion Decay Geometry: halo of thickness z Diffusion: diffusion in the galactic magnetic field inhomogeneities, propagating through the ISM (D 0, δ, R 0 ) Convection: galactic wind with velocity V c and gradient dv c dz Reacceleration: interstellar turbulence with Alfvén velocity V A Sources: SNe shocks produce power law spectra in energy (γ 1,2 indices) 7 fundamental parameters space to fix CR propagation + N specific injection indices
Interstellar astrophysics uncertainties before AMS-02 Rescaled Antiproton Flux Rescaled total antiproton flux for Dark Matter search Propagation models: almost two orders of magnitude, one above one below the MED propagation values set
MonteCarlo Markov Chain Approach: parameters scan with AMS data multiple constraints to find a single CRs propagation scheme
MCMC + GALPROP Approach 1. Fitting AMS-02 data with Monte-Carlo-Markov-Chain methods applied to GALPROP, a definite propagation scheme has been achieved 2. With this single set of propagation parameters, we can describe all the CR phenomenology, from heavy nuclei to protons, electrons and antiprotons 3. Once fixed the propagation parameters we have also removed the secondary background for DM searches in the p p channel The CosRay-MC software we implemented in Bologna (developed from COSMOMC package) can be run @ CNAF: tens of thousands simulations in few days
MCMC Matrix With p, He, e- spectra, B/C (and preliminary nuclei spectra) we can easily constrain, for the first time, the fundamental parameters that describe the CR propagation and the galactic physics Va : Alfvén velocity VC : convection velocity R0 : diffusion break position
Results: Spectra and Ratios Fits @ % level Local Interstellar Spectrum protons
Results: Spectra and Ratios Fits @ % level Helium 9
Results: Spectra and Ratios Fits @ % level electrons
Positrons Positrons rise after 20 GeV incompatible with secondaries predictions
Pulsars Problem Anyone of two well-known nearby pulsars, Geminga and Monogem, can satisfactorily provide enough positrons to reproduce AMS-02 observations: AMS 0.030 The predicted anisotropy level is, at present, consistent with limits from Fermi-LAT and AMS-02
CR Physics Improvements Before AMS-02 After AMS-02 Unit Error (%) z kpc 54% D 0 /10^28 cm 2 s 1 96% δ 57% V Alfven km s 1 89% V 0conv km s 1 100% dv C dz km s 1 kpc 1 100% Error (%) Improvement factor ε before 4% 14 6% 16 5% 11 8% 11 10% 10 10% 10 ε after Before AMS-02 we were not able to fix the CR propagation physics: the parameters lied in very wide ranges. With AMS-02 data is finally possible to achive a consistent best fit: the errors associated to the fundamental propagation parameters z, D 0xx, δ 1,2 are greatly reduced. We still have some degeneracies/uncertainties which afflict secondaries predictions. A factor 10 (or greater) of improvement for fundamental parameters
Uncertainties in p channel: Propagation vs Nuclear critical point (p + p ISM p + X) (ICRC p p data) Nuclear and propagation uncertainties are comparable but in the high energy region above 30 GeV propagation error is lower than the nuclear one. Adding further AMS data sets to the analysis (B, C, O, Li, Be/B ) the propagation error will be reduced: astrophysical uncertainties are now less relevant than nuclear ones 14
Low energy physics
AMS Voyager1 interplay We can calibrate the LISs (Local Interstellar Spectra) for the fundamental CRs species interpolating AMS-02 and Voyager-1
AMS Voyager1 interplay Simulated proton and He LISs have been compared to Voyager1 Once modulated, the LISs correctly reproduce AMS-02 (and also PAMELA, BESS, AMS-01 )
Dark Matter Search in space with AMS-02: towards a heavy candidate hunt
Heavy Candidates for AMS-02 SUSY Wino Neutralino M = 1 TeV p M = 2 TeV e + KK Universal Extra Dimension (UED) vector boson e + M = 1.5 TeV Scalar Multiplet With a definite production and propagation picture we remove the background for the DM search, highlighting possible new phenomena and characterizing viable candidates
AMS-02 antideuteron search d
AMS-02 results: how can we read them?
B/C: preliminary hints 7M Carbons, 2M Borons The B/C ratio does not rise at high energies, up to about 700 GeV/n: SNRs reacceleration models are ill-favored; We can deduce the diffusion shape (the diffusion index); The quite slow decreasing of the B/C ratio above 50 GeV/n seems to allow us to exclude the anisotropic CR propagation models and long galactic permanence models, such as Cowsik s. 22
Proton over Helium ratio The ratio is featureless: this could implies the same mechanism for the breaks -> a propagation effect?
Hadrons anomalies w.r.t the Standard Model Change of slope (~0.1) after about 330 GeV/n for protons and Helia: diffusive δ 2 δ 3 effects? (SNe shock modelization, or nearby high energy sources) Differences in gamma indices ( γ p He ~0.07) between p and He, which seems to remain constant at all energies Unexpected rise of the pure secondary Lithium spectrum: this could force us to change the orthodoxy
AMS-02 data allow a deeper understanding of the «High Energy Universe»: the unprecedented precision permits to fix CRs production and propagation parameters, with excellent nuclei fits up to the TeV scale; AMS-02 gives the possibility to discover fine phenomena that emerge from predicted nuclei spectra and ratios; Removing astrophysical uncertainties using AMS-02 data means reducing the background for the dark matter indirect search, which is now more concrete; For the first time astrophysical uncertainties became less relevant than the nuclear cross sections ones; The characterization of the Local Interstellar Spectra of CRs has a key role in the understanding of Galactic and Heliosphere physics: AMS-Voyager interplay might be exploit to build a unitary description of CR physics.