Measurement of the Cosmic Ray e+ plus e- spectrum from 20 GeV to 1 TeV with the Fermi Large Area Telescope

TL;DR

This paper reports precise measurements of the cosmic ray electron spectrum from 20 GeV to 1 TeV using the Fermi Large Area Telescope, revealing a smooth power-law decline without prominent features.

Contribution

It introduces an efficient electron detection method with high background rejection, enabling accurate spectrum measurement up to 1 TeV with the Fermi LAT.

Findings

Electron spectrum follows a E^(-3.0) power law.

No prominent spectral features observed.

Data consistent with conventional diffusive models.

Abstract

Designed as a high-sensitivity gamma-ray observatory, the Fermi Large Area Telescope is also an electron detector with a large acceptance exceeding 2m^2 sr at 300 GeV. Building on the gamma-ray analysis, we have developed an efficient electron detection strategy which provides sufficient background rejection for measurement of the steeply-falling electron spectrum up to 1 TeV. Our high precision data show that the electron spectrum falls with energy as E^(-3.0) and does not exhibit prominent spectral features. Interpretations in terms of a conventional diffusive model as well as a potential local extra component are briefly discussed.