AMS-02 fits dark matter

2018

In this work we perform a comprehensive statistical analysis of the AMS-02 electron, positron fluxes and the antiproton-to-proton ratio in the context of a simplified dark matter model. We include known, standard astrophysical sources and a dark matter component in the cosmic ray injection spectra. To predict the AMS-02 observables we use propagation parameters extracted from observed fluxes of heavier nuclei and the low energy part of the AMS-02 data. We assume that the dark matter particle is a Majorana fermion coupling to third generation fermions via a spin-0 mediator, and annihilating to multiple channels at once. The simultaneous presence of various annihilation channels provides the dark matter model with additional flexibility, and this enables us to simultaneously fit all cosmic ray spectra using a simple particle physics model and coherent astrophysical assumptions. Our results indicate that AMS-02 observations are not only consistent with the dark matter hypothesis within...

Journal of Cosmology and Astroparticle Physics, 2015

— AMS-02 is running since four years: a powerful apparatus for dark matter searches has been setup , in order to study the important antiparticle to particle ratios and cosmic leptons and nuclei spectra, up to the TeV scale. Official papers dedicated to hadronic physics are incoming. The unprecedented precision of AMS-02 data permits to greatly reduce the astrophysical uncertainties which affect cosmic rays (CR) propagation, allowing to study CR anomalies and highlight new phenomena, to corroborate or falsify present dark matter (DM) theories and to explore the TeV-ish dark matter scenario opportunities.

Journal of Cosmology and Astroparticle Physics, 2016

Physical Review Letters, 2011

Physical Review D, 2011

The unexpected energy spectrum of the positron/electron ratio is interpreted astrophys-ically, with a possible exception of the 100-300 GeV range. The data indicate that this ratio, after a decline between 0.5 − 8 GeV, rises steadily with a trend towards saturation at 200-400GeV. These observations (except for the trend) appear to be in conflict with the diffusive shock acceleration (DSA) mechanism, operating in a single supernova remnant (SNR) shock. We argue that e + /e − ratio can still be explained by the DSA if positrons are accelerated in a subset of SNR shocks which: (i) propagate in clumpy gas media, and (ii) are modified by accelerated CR protons. The protons penetrate into the dense gas clumps upstream to produce positrons and, charge the clumps positively. The induced electric field expels positrons into the upstream plasma where they are shock-accelerated. Since the shock is modified, these positrons develop a harder spectrum than that of the CR electrons accelerated in other SNRs. Mixing these populations explains the increase in the e + /e − ratio at E > 8 GeV. It decreases at E < 8 GeV because of a subshock weakening which also results from the shock modification. Contrary to the expelled positrons, most of the antiprotons, electrons, and heavier nuclei, are left unaccelerated inside the clumps. Scenarios for the 100-300 GeV AMS-02 fraction exceeding the model prediction, including, but not limited to, possible dark matter contribution, are also discussed.