July 29, 2015 to August 6, 2015
World Forum
Europe/Amsterdam timezone

Uncertainties on propagation parameters: impact on the interpretation of the positron fraction

Aug 4, 2015, 4:00 PM
Amazon Foyer (World Forum)

Amazon Foyer

World Forum

Churchillplein 10 2517 JW Den Haag The Netherlands
Board: 225
Poster contribution CR-TH Poster 3 CR


yoann genolini (LAPTh)


The positron fraction in cosmic rays has recently been measured with improved accuracy up to 500 GeV, and it was found to be a steadily increasing function of energy above $\sim$ 10 GeV. This behaviour contrasts with standard astrophysical mechanisms, in which positrons are secondary particles, produced in the interactions of primary cosmic rays during their propagation in the interstellar medium. The observed anomaly in the positron fraction triggered a lot of excitement, as it could be interpreted as an indirect signature of the presence of dark matter species in the Galaxy, the so-called weakly interacting massive particles (WIMPs). Alternatively, it could be produced by nearby sources, such as pulsars. These hypotheses are probed in light of the latest AMS-02 positron fraction measurements. The cosmic ray positron transport in the Galaxy is described using a semi-analytic two-zone model. For consistency, the secondary and primary components of the positron flux are calculated together with the same propagation model. We show that the results inferred for both hypotheses crucially depend on the propagation parameters, estimated with the Boron-to-Carbon ratio. Their uncertainties turn out to be very significant, and overshadow even the statical errors from the positron data.
Collaboration -- not specified --
Registration number following "ICRC2015-I/" 839

Primary authors

Antje Putze (Centre National de la Recherche Scientifique (FR)) Genevieve Belanger (LAPP Annecy) Mathieu Boudaud (LAPTh Annecy France) Sami Caroff (Centre National de la Recherche Scientifique (FR)) Sandy Aupetit (Centre National de la Recherche Scientifique (FR)) yoann genolini (LAPTh)


Corinne Goy (Centre National de la Recherche Scientifique (FR)) Li Tao (Centre National de la Recherche Scientifique (FR)) Manuela Vecchi (Universidade de Sao Paulo (BR)) PIERRE SALATI (LAPTh & Université de Savoie Mont Blanc) Sylvie Rosier (Centre National de la Recherche Scientifique (FR)) Vincent Poireau (Centre National de la Recherche Scientifique (FR)) Mr Vivian Poulin (LAPTh)

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