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The flux of positrons and electrons ($e^+ + e^-$) has been measured by the$Fermi$ Large Area Telescope (LAT) in the energy range between 7 GeV and 2 TeV.We discuss a number of interpretations of Pass 8 $Fermi$-LAT $e^+ + e^-$spectrum, combining electron and positron emission from supernova remnants(SNRs) and pulsar wind nebulae (PWNe), or produced by the collision of cosmicrays with the interstellar medium. We find that the $Fermi$-LAT spectrum iscompatible with the sum of electrons from a smooth SNR population, positronsfrom cataloged PWNe, and a secondary component. If we include in our analysisconstraints from AMS-02 positron spectrum, we obtain a slightly worse fit tothe $e^+ + e^-$ $Fermi$-LAT spectrum, depending on the propagation model. As anadditional scenario, we replace the smooth SNR component within 0.7 kpc withthe { individual sources} found in Green's catalog of Galactic SNRs. We findthat separate consideration of far and near sources helps to reproduce the $e^++ e^-$ $Fermi$-LAT spectrum. However, we show that the fit degrades when theradio constraints on the positron emission from Vela SNR (which is the maincontributor at high energies) are taken into account. We find that a break inthe power-law injection spectrum at about 100 GeV can also reproduce themeasured $e^+ + e^-$ spectrum} and, among the cosmic-ray propagation modelsthat we consider, no reasonable break of the power-law dependence of thediffusion coefficient can modify the electron flux enough to reproduce theobserved shape.

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