Theoretical interpretation of Pass 8 Fermi-LAT e+ + e- data

Abstract

The Fermi-LAT Collaboration has recently reported a new measurement of the inclusive cosmic-ray positron and electron spectrum in the energy range between 7 GeV and 2 TeV, obtained with almost seven years of all sky data processed with the Pass 8 event reconstruction. Here we discuss several interpretations of these results within a model where electrons and positrons are emitted by supernova remnants (SNRs) and pulsar wind nebulae (PWNe) or produced by the collision of cosmic rays with the interstellar medium. In particular, we study the emission from PWNe in relation to the limits set by the AMS-02 measurement of the positron flux. We investigate in a quantitative way the interplay between far and local SNRs by focusing on the impact of the radio constraints on the emission of electrons from the Vela SNR (which is possibly the main contributor at high energies). Furthermore, we discuss the possibility to exploit the features of the Fermi-LAT data to deduce some distinctive properties of the SNR electron spectrum at the injection, in view of the uncertainties associated to the modelling of cosmic-ray propagation in the Galaxy.